Mathematics Part Ii Chapter 7 Integrals
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    NCERT Solution For Class 12 Mathematics Mathematics Part Ii

    Integrals Here is the CBSE Mathematics Chapter 7 for Class 12 students. Summary and detailed explanation of the lesson, including the definitions of difficult words. All of the exercises and questions and answers from the lesson's back end have been completed. NCERT Solutions for Class 12 Mathematics Integrals Chapter 7 NCERT Solutions for Class 12 Mathematics Integrals Chapter 7 The following is a summary in Hindi and English for the academic year 2021-2022. You can save these solutions to your computer or use the Class 12 Mathematics.

    Question 1
    CBSEENMA12032343

    Evaluate integral from 1 to 2 of straight x space dx as the limit of a sum.

    Solution

    Comparing integral from 1 to 2 of straight x space dx space space with space integral from straight a to straight b of straight f left parenthesis straight x right parenthesis space dx comma space space we space get comma
                   straight f left parenthesis straight x right parenthesis space equals space straight x comma space space space straight a space equals space 1 comma space space straight b space equals space 2
    therefore space space space straight f left parenthesis straight a right parenthesis space equals space straight a comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight a plus straight h comma space space straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight a plus 2 straight h comma space...... straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight a plus left parenthesis straight n minus 1 right parenthesis straight h
    Now   integral from straight a to straight b of straight f left parenthesis straight x right parenthesis space equals space stack Lt. straight h with straight h rightwards arrow 0 below left square bracket space straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis space plus space....... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                                                                                                  where n h = b - a
    rightwards double arrow        integral from straight a to straight b of xdx space equals space Lt with straight h rightwards arrow 0 below straight h left square bracket straight a plus straight a left parenthesis straight a plus straight h right parenthesis plus left parenthesis straight a plus 2 space straight h right parenthesis space plus space... plus left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
                              equals stack Lt space straight h with straight h rightwards arrow 0 below left square bracket left parenthesis straight a plus straight a plus straight a plus... to space straight n space terms right parenthesis space plus space straight h open curly brackets 1 plus 2 plus 3 plus.... plus left parenthesis straight n minus 1 right parenthesis close curly brackets right square bracket
                             equals space Lt with straight h rightwards arrow 0 below straight h open square brackets na plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n minus 1 plus 1 right parenthesis over denominator 2 end fraction close square brackets space space space space space open square brackets therefore 1 plus 2 plus 3 plus... plus straight n space equals space fraction numerator straight n left parenthesis straight n plus 1 right parenthesis over denominator 2 end fraction close square brackets
equals Lt with straight h rightwards arrow 0 below straight h open square brackets straight n space straight a plus fraction numerator straight n left parenthesis straight n minus 1 right parenthesis over denominator 2 end fraction straight h close square brackets space space equals Lt with straight h rightwards arrow 0 below open square brackets straight a space left parenthesis nh right parenthesis space plus space fraction numerator straight n space straight h left parenthesis nh minus straight h right parenthesis over denominator 2 end fraction close square brackets
equals Lt with straight h rightwards arrow 0 below open square brackets straight a space left parenthesis straight b minus straight a right parenthesis space plus space fraction numerator left parenthesis straight b minus straight a right parenthesis space left parenthesis straight b minus straight a minus straight h right parenthesis over denominator 2 end fraction close square brackets
equals space straight a left parenthesis straight b minus straight a right parenthesis space plus space fraction numerator left parenthesis straight b minus straight a right parenthesis space left parenthesis straight b minus straight a minus 0 right parenthesis over denominator 2 end fraction space equals space straight a space left parenthesis straight b minus straight a right parenthesis space plus fraction numerator left parenthesis straight b minus straight a right parenthesis squared over denominator 2 end fraction
equals space left parenthesis straight b minus straight a right parenthesis open square brackets straight a plus fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets space equals space left parenthesis straight b minus straight a right parenthesis open parentheses fraction numerator straight b plus straight a over denominator 2 end fraction close parentheses
    therefore space space space space space integral from straight a to straight b of xdx space equals space 1 half left parenthesis straight b squared minus straight a squared right parenthesis
    Put a = 1,  b = 2
    therefore space space space space space space space space space space space space space integral from 1 to 2 of xdx space equals space 1 half left parenthesis 4 minus 1 right parenthesis space equals space 3 over 2

    Question 2
    CBSEENMA12032344

    Evaluate the following definite integrals as limit of a sum.
    integral from straight a to straight b of straight x space dx

    Solution

    Comparing integral subscript straight a superscript straight b xdx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                     straight f left parenthesis straight x right parenthesis space equals space straight x
    therefore            straight f left parenthesis straight a right parenthesis space equals space straight a plus straight h
        straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight a plus 2 straight h
    ......................................
    straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight a plus stack straight n minus 1 with bar on top straight h
    Now integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
                               equals space Lt with straight h rightwards arrow 0 below straight h left square bracket straight a plus left parenthesis straight a plus straight h right parenthesis plus left parenthesis straight a plus 2 straight h right parenthesis plus.... plus left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
equals space Lt with straight h rightwards arrow 0 below straight h left square bracket straight n space straight a space plus space straight h space open curly brackets 1 plus 2 plus 3 plus....... plus left parenthesis straight n minus 1 right parenthesis close curly brackets right square bracket
equals space Lt with straight h rightwards arrow 0 below straight h open square brackets straight n space straight a space plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below open square brackets straight a left parenthesis straight n. straight h right parenthesis space plus space fraction numerator left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets straight a left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a minus straight h right parenthesis space left parenthesis straight b minus straight a right parenthesis over denominator 2 end fraction close square brackets
equals space straight a left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a minus 0 right parenthesis space left parenthesis straight b minus straight a right parenthesis over denominator 2 end fraction
equals space straight a left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a right parenthesis squared over denominator 2 end fraction space equals space left parenthesis straight b minus straight a right parenthesis space open square brackets straight a plus fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets
equals space left parenthesis straight b minus straight a right parenthesis open square brackets fraction numerator 2 straight a plus straight b minus straight a over denominator 2 end fraction close square brackets space equals space left parenthesis straight b minus straight a right parenthesis open parentheses fraction numerator straight b plus straight a over denominator 2 end fraction close parentheses space equals space 1 half left parenthesis straight b squared minus straight a squared right parenthesis.

    Question 3
    CBSEENMA12032345

    Evaluate the following definite integral as limit of a sum.
    integral subscript 1 superscript 2 xdx



    Solution

    Comparing integral subscript 1 superscript 2 xdx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space space we space get comma
       straight f left parenthesis straight x right parenthesis space equals space straight x comma space space space straight a space equals space 1 comma space space space straight b space equals space space 2
    therefore space space space space straight f left parenthesis straight a right parenthesis space equals space straight a comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight a plus straight h comma space space straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight a plus 2 straight h comma space...... comma space straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight a plus left parenthesis straight n minus 1 right parenthesis space straight h
    Now integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis close square brackets
    rightwards double arrow  integral subscript straight a superscript straight b xdx space equals space Lt with straight h rightwards arrow 0 below straight h space left square bracket straight a plus left parenthesis straight a plus straight h right parenthesis plus left parenthesis straight a plus 2 straight h right parenthesis plus... plus left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                         equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets left parenthesis straight a plus straight a plus straight a plus.... to space straight n space terms right parenthesis space plus space straight h space open curly brackets 1 plus 2 plus 3 plus.... plus left parenthesis straight n minus 1 right parenthesis close curly brackets close square brackets
equals space Lt with straight h rightwards arrow 0 below straight h open square brackets straight n space straight a space plus space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n minus 1 plus 1 right parenthesis over denominator 2 end fraction close square brackets space space open square brackets because 1 plus 2 plus 3 plus.... plus straight n space equals space fraction numerator straight n left parenthesis straight n plus 1 right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below straight h open square brackets straight n space straight a plus space fraction numerator straight n left parenthesis straight n minus 1 right parenthesis over denominator 2 end fraction straight h close square brackets space equals space Lt with straight h rightwards arrow 0 below open square brackets straight a left parenthesis nh right parenthesis plus fraction numerator nh left parenthesis nh minus straight h right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets straight a space left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a right parenthesis left parenthesis straight b minus straight a minus straight b right parenthesis over denominator 2 end fraction close square brackets
equals space straight a left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a right parenthesis left parenthesis straight b minus straight a minus 0 right parenthesis over denominator 2 end fraction space equals space straight a left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a right parenthesis squared over denominator 2 end fraction
equals space left parenthesis straight b minus straight a right parenthesis space open square brackets straight a plus fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets space equals space left parenthesis straight b minus straight a right parenthesis space open parentheses fraction numerator straight b plus straight a over denominator 2 end fraction close parentheses
    therefore space space space space integral subscript straight a superscript straight b straight x space dx space equals space 1 half left parenthesis straight b squared minus straight a squared right parenthesis
space space space space space space space space Put space straight a space equals 1 comma space space space straight b space equals space 2
therefore space space space integral subscript 1 superscript 2 straight x space dx space equals space 1 half left parenthesis 4 minus 1 right parenthesis space equals space 3 over 2
                         

    Question 4
    CBSEENMA12032346

    Evaluate the following definite integral as limit of a sum.
    integral subscript 0 superscript 5 left parenthesis straight x minus 1 right parenthesis dx


    Solution

    Comparing integral subscript 0 superscript 5 left parenthesis straight x minus 1 right parenthesis dx space with space integral subscript straight a superscript straight b space straight f left parenthesis straight x right parenthesis space dx comma space space space we space get comma
       f(x) = x - 1,  a = 0,  b = 5
    straight f left parenthesis straight a plus 2 space straight h right parenthesis space equals space straight f left parenthesis 2 space straight h right parenthesis space equals space 2 space straight h space minus space 1 comma space space..... comma space space left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top straight h right parenthesis space equals space left parenthesis straight n minus 1 right parenthesis space straight h space minus 1
    Now integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis close square brackets
              equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets left parenthesis negative 1 right parenthesis plus left parenthesis straight h minus 1 right parenthesis plus left parenthesis 2 straight h minus 1 right parenthesis plus.... plus open curly brackets left parenthesis straight n minus 1 right parenthesis straight h minus 1 close curly brackets close square brackets
equals space Lt with straight h space rightwards arrow 0 below space straight h open square brackets negative straight n plus straight h open curly brackets 1 plus 2 plus 3 plus... plus left parenthesis straight n minus 1 right parenthesis close curly brackets close square brackets space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets negative straight n plus straight h fraction numerator left parenthesis straight n minus 1 minus straight n right parenthesis over denominator 2 end fraction close square brackets
          equals space Lt with straight h rightwards arrow 0 below open square brackets negative nh plus fraction numerator left parenthesis straight n space straight h right parenthesis space left parenthesis nh space minus space straight h right parenthesis over denominator 2 end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below open square brackets negative left parenthesis 5 minus 0 right parenthesis plus left parenthesis 5 minus 0 right parenthesis fraction numerator left parenthesis 5 minus 0 minus straight h right parenthesis over denominator 2 end fraction close square brackets
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space space straight n space straight h space equals space straight b space minus straight a space equals space 5 space minus space 0 close square brackets
equals space minus 5 plus fraction numerator 5 left parenthesis 5 minus 0 right parenthesis over denominator 2 end fraction equals negative 5 plus 25 over 2 equals fraction numerator negative 10 plus 25 over denominator 2 end fraction equals 15 over 2
                         
                         

    Question 5
    CBSEENMA12032347

    Evaluate the following integral as the limit of a sum:
    integral subscript 1 superscript 3 left parenthesis 2 straight x plus 3 right parenthesis dx

    Solution

    Comparing integral subscript 1 superscript 3 left parenthesis 2 straight x plus 3 right parenthesis dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma we get
             f(x) = 2x +3 ,   a = 1,  b = 3
    therefore    straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 2 plus 3 space equals space 5 comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space 2 left parenthesis 1 plus straight h right parenthesis space plus space 3 space equals space 5 space plus space 2 straight h
             f(a+2h) = f(1+2h) = 2(1+2h)+3 = 5+4h
              ...     ...      ...        ...         ...          ...
            straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space 2 open curly brackets 1 plus left parenthesis straight n minus 1 right parenthesis space straight h close curly brackets space plus 3 space equals space 5 plus 2 left parenthesis straight n minus 1 right parenthesis space straight h
    Now, integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below straight h space open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus top enclose straight n minus 1 end enclose space straight h right parenthesis close square brackets
    rightwards double arrow space space space integral subscript 1 superscript 3 left parenthesis 2 straight x plus 3 right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below straight h left square bracket 5 plus left parenthesis 5 plus 2 straight h right parenthesis plus left parenthesis 5 plus 4 straight h right parenthesis plus.... plus open curly brackets 5 plus 2 left parenthesis straight n minus 1 right parenthesis space straight h close curly brackets
                                      equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 5 straight n plus 2 straight h open curly brackets 1 plus 2 plus 3 plus.... plus left parenthesis straight n minus 1 right parenthesis close curly brackets right square bracket
equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets 5 straight n plus 2 straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n over denominator 2 end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below open square brackets 5 space straight n space straight h space plus left parenthesis straight n space straight h right parenthesis space left parenthesis nh space minus straight h right parenthesis close square brackets
equals space Lt with straight h rightwards arrow 0 below space left square bracket space 5 space left parenthesis 2 right parenthesis space plus space left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis right square bracket space space space space space space space space space space space space space space space space open square brackets because space straight n space straight h space space equals space straight b space minus straight a space equals space 3 space minus space 1 space equals space 2 close square brackets
space equals space 5 space left parenthesis 2 right parenthesis space plus space 2 left parenthesis 2 minus 0 right parenthesis space equals space 10 plus 4 space equals space 14

    Question 6
    CBSEENMA12032348

    Evaluate
    integral subscript straight a superscript straight b straight x squared space dx  as the limit of sum.

    Solution

    Comparing integral subscript straight a superscript straight b straight x squared dx with integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space space we space get comma
                              straight f left parenthesis straight x right parenthesis space equals space straight x squared
    therefore                     straight f left parenthesis straight a right parenthesis space equals space straight a squared
                   straight f left parenthesis straight a plus straight h right parenthesis space equals space left parenthesis straight a plus straight h right parenthesis squared
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space left parenthesis straight a plus 2 straight h right parenthesis squared
                  .............................
             straight f left parenthesis straight a plus stack straight n minus 1 with bar on top minus straight h right parenthesis space equals space left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis squared
    Now       integral subscript straight a superscript straight b space straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
    where      nh space equals space straight b minus straight a
    therefore          integral subscript straight a superscript straight b straight x squared dx space equals space Lt with straight h rightwards arrow 0 below straight h left square bracket straight a squared plus left parenthesis straight a plus straight h right parenthesis squared plus left parenthesis straight a plus 2 straight h right parenthesis squared plus.... plus left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis squared
             equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket left parenthesis straight a squared plus straight a squared plus straight a squared plus..... space to space straight n space term right parenthesis space plus space 2 space straight a space straight h space left curly bracket 1 plus 2 plus 3 plus... plus stack straight n minus 1 with bar on top right curly bracket space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space
                                                                              plus straight h squared left curly bracket 1 squared plus 2 squared plus 3 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared right curly bracket right square bracket
    equals space Lt with straight h rightwards arrow 0 below space straight h space space open square brackets na squared plus 2 ah. fraction numerator left parenthesis straight n minus 1 right parenthesis straight n over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis left parenthesis straight n right parenthesis left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets straight a squared nh plus straight a left parenthesis nh minus straight h right parenthesis left parenthesis nh right parenthesis plus fraction numerator left parenthesis nh minus straight h right parenthesis left parenthesis nh right parenthesis left parenthesis 2 nh minus straight h right parenthesis over denominator 6 end fraction close square brackets
    equals space Lt with straight h rightwards arrow 0 below open square brackets straight a squared left parenthesis straight b minus straight a right parenthesis plus straight a left parenthesis straight a minus straight b minus straight h right parenthesis space left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a minus straight h right parenthesis space left parenthesis straight b minus straight a right parenthesis left parenthesis 2 straight b minus 2 straight a minus straight h right parenthesis over denominator 6 end fraction close square brackets
equals space straight a squared left parenthesis straight b minus straight a right parenthesis plus straight a left parenthesis straight b minus straight a minus 0 right parenthesis left parenthesis straight b minus straight a right parenthesis plus fraction numerator left parenthesis straight b minus straight a minus 0 right parenthesis left parenthesis straight b minus straight a right parenthesis left parenthesis 2 straight b minus 2 straight a minus 0 right parenthesis over denominator 6 end fraction
equals space straight a squared left parenthesis straight b minus straight a right parenthesis plus straight a left parenthesis straight b minus straight a right parenthesis squared plus 1 third left parenthesis straight b minus straight a right parenthesis cubed space equals space left parenthesis straight b minus straight a right parenthesis open square brackets straight a squared plus straight a left parenthesis straight b minus straight a right parenthesis plus 1 third left parenthesis straight b minus straight a right parenthesis squared close square brackets
    equals space left parenthesis straight b minus straight a right parenthesis open square brackets fraction numerator 3 straight a squared plus 3 straight a left parenthesis straight b minus straight a right parenthesis plus left parenthesis straight b minus straight a right parenthesis squared over denominator 3 end fraction close square brackets
    equals space fraction numerator left parenthesis straight b minus straight a right parenthesis over denominator 3 end fraction left square bracket 3 space straight a squared plus 3 space straight a space straight b space minus space 3 space straight a squared space plus space straight b squared space plus space straight a squared space minus space 2 space straight a space straight b right square bracket
equals space 1 third left parenthesis straight b minus straight a right parenthesis space left parenthesis straight a squared plus straight b squared plus ab right parenthesis space equals space 1 third left parenthesis straight b cubed minus straight a cubed right parenthesis

    Question 7
    CBSEENMA12032349

    Evaluate  integral subscript 1 superscript 3 straight x squared space dx as the limit of a sum.

    Solution

    Comparing integral subscript 1 superscript 3 straight x squared dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space space we space get
               straight f left parenthesis straight x right parenthesis space equals space straight x squared comma space space straight a space equals space 1 comma space space straight b space equals space 3
    therefore space space space straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 1
space space space space space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space left parenthesis 1 plus straight h right parenthesis squared
space space space space straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space left parenthesis 1 plus 2 straight h right parenthesis squared
space space space straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis 1 plus stack straight n minus 1 with bar on top straight h right parenthesis squared
    Now, integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h close square brackets
    where n h = b - a = 3 - 1 = 2
    rightwards double arrow space space space integral subscript 1 superscript 3 straight x squared dx space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 1 plus left parenthesis 1 plus straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis squared plus.... plus left parenthesis 1 plus stack straight n minus 1 with bar on top straight h right parenthesis squared close square brackets
           space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket left parenthesis 1 plus 1 plus 1 plus...... space to space straight n space terms right parenthesis space plus space 2 space straight h space open curly brackets 1 plus 2 plus 3 plus... plus left parenthesis straight n minus 1 right parenthesis close curly brackets
                                                                        plus space straight h squared space open curly brackets 1 squared plus 2 squared plus 3 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets right square bracket
           equals space Lt with straight h rightwards arrow 0 below straight h open square brackets straight n plus 2 space straight h space fraction numerator left parenthesis straight n minus 1 right parenthesis straight n over denominator 2 end fraction plus straight h squared space fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets space straight n space straight h space plus space left parenthesis straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus space straight h right parenthesis plus fraction numerator left parenthesis space straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis over denominator 6 end fraction space close square brackets
    equals space Lt with straight h rightwards arrow 0 below open square brackets 2 plus left parenthesis 2 right parenthesis left parenthesis 2 minus straight h right parenthesis plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis space left parenthesis 4 minus straight h right parenthesis over denominator 6 end fraction close square brackets space space space space space space open square brackets because space straight n space straight h space equals space 1 close square brackets
equals space 2 plus left parenthesis 2 right parenthesis space left parenthesis 2 minus 0 right parenthesis space plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus 0 right parenthesis space left parenthesis 4 minus 0 right parenthesis over denominator 6 end fraction space equals 2 plus 4 plus 8 over 3 space equals space 26 over 3
           

    Question 8
    CBSEENMA12032350

    Evaluate integral subscript 1 superscript 4 left parenthesis straight x squared minus straight x right parenthesis space dx  as the limit of a sum.

    Solution

    Comparing integral subscript 1 superscript 4 left parenthesis straight x squared minus straight x right parenthesis dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                     straight f left parenthesis straight x right parenthesis space equals space straight x squared minus straight x comma space space straight a space equals space 1 comma space space space space straight b space equals space 4
                     space space space space space space straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 1 minus 1 space equals space 0
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space left parenthesis 1 plus straight h right parenthesis squared minus left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space left parenthesis 1 plus 2 straight h right parenthesis squared minus left parenthesis 1 plus 2 straight h right parenthesis
                      ..................................................................
               straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis 1 plus stack straight n minus 1 with bar on top right parenthesis squared minus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus..... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
           therefore space space space integral subscript 1 superscript 4 left parenthesis straight x squared minus straight x right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 0 plus open curly brackets left parenthesis 1 plus straight h right parenthesis squared minus left parenthesis 1 plus straight h right parenthesis close curly brackets space plus space open curly brackets left parenthesis 1 plus 2 straight h right parenthesis squared minus left parenthesis 1 plus 2 straight h right parenthesis close curly brackets plus.....
                                                                                       plus open curly brackets left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared minus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis close curly brackets right square bracket
                     equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket open curly brackets straight n plus 2 straight h space left parenthesis 1 plus 2 plus 3 plus... plus stack straight n minus 1 with bar on top right parenthesis plus straight h squared left parenthesis 1 squared plus 2 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets
                                                                                   negative open curly brackets straight n plus left parenthesis 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right parenthesis space straight h close curly brackets right square bracket

                equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets straight n plus 2 straight h plus fraction numerator left parenthesis straight n minus 1 right parenthesis straight n over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction minus straight n minus fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction straight h close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets straight n space straight h space plus space left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis nh right parenthesis space plus space fraction numerator left parenthesis nh minus straight h right parenthesis space left parenthesis nh right parenthesis space left parenthesis 2 nh minus straight h right parenthesis over denominator 6 end fraction minus nh minus fraction numerator left parenthesis nh minus straight h right parenthesis space left parenthesis nh right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets 3 plus left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis plus space fraction numerator left parenthesis 3 minus straight h right parenthesis space left parenthesis 6 minus straight h right parenthesis over denominator 6 end fraction minus 3 minus fraction numerator left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis over denominator 2 end fraction close square brackets
                                                                                                open square brackets because space space straight n space straight h space equals space straight b space minus straight a space equals space 4 space minus space 1 space equals space 3 close square brackets
                space equals 3 plus left parenthesis 3 minus 0 right parenthesis space left parenthesis 3 right parenthesis space plus fraction numerator left parenthesis 3 minus 0 right parenthesis space left parenthesis 3 right parenthesis space left parenthesis 6 minus 0 right parenthesis over denominator 6 end fraction minus 3 minus fraction numerator left parenthesis 3 minus 0 right parenthesis space left parenthesis 3 right parenthesis over denominator 2 end fraction
space equals space 3 plus 9 plus 9 minus 3 minus 9 over 2 space equals space 27 over 2

    Question 9
    CBSEENMA12032351

    Evaluate integral subscript 1 superscript 2 space left parenthesis 3 straight x squared plus 5 straight x right parenthesis space dx as limit of sums.

    Solution

    Comparing integral subscript 1 superscript 2 left parenthesis 3 space straight x squared plus 5 straight x right parenthesis space dx space with space integral subscript straight a superscript straight b space straight f left parenthesis straight x right parenthesis space dx comma space we get
                  straight f left parenthesis straight x right parenthesis space equals space 3 straight x squared plus 5 straight x comma space space straight a space equals space 1 comma space space straight b space equals space 2
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 3 plus 5
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space 3 left parenthesis 1 plus straight h right parenthesis squared plus 5 left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space 3 left parenthesis 1 plus 2 straight h right parenthesis squared plus 5 left parenthesis 1 plus 2 straight h right parenthesis
                ....................................................................
                 straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space 3 open curly brackets 1 plus left parenthesis straight n minus 1 right parenthesis space straight h close curly brackets squared plus 5 open curly brackets 1 plus left parenthesis straight n minus 1 right parenthesis space straight h close curly brackets
    Now    integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus..... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis
    rightwards double arrow      integral subscript 1 superscript 2 left parenthesis 3 straight x squared plus 5 straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket open curly brackets 3 plus 5 close curly brackets plus open curly brackets 3 space left parenthesis 1 plus straight h right parenthesis squared space plus space 5 space left parenthesis 1 plus straight h right parenthesis close curly brackets space space space space space space space space space space
                               plus open curly brackets 3 space left parenthesis 1 plus 2 space straight h right parenthesis squared space plus space 5 left parenthesis 1 plus 2 straight h right parenthesis close curly brackets space plus space....... plus open curly brackets 3 space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus 5 left parenthesis 1 plus stack straight n minus 1 with bar on top straight h right parenthesis close curly brackets right square bracket
              equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket left parenthesis 3 space straight n plus space 5 space straight n space plus space 6 space straight h space left parenthesis 1 plus 2 plus..... plus stack straight n minus 1 with bar on top right parenthesis plus 5 space straight h space left parenthesis 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right parenthesis space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space
                                                                     plus space 3 space straight h squared space open curly brackets 1 squared plus 2 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets right square bracket
    equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 8 space straight n space plus 6 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator straight n end fraction plus fraction numerator space 5 space straight h space left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus space 3 space straight h squared space fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
     equals space Lt with straight h rightwards arrow 0 below open square brackets 8 space straight n space straight h space plus space 3 space left parenthesis straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus straight h right parenthesis space space plus 5 over 2 left parenthesis space straight n space straight h right parenthesis space left parenthesis nh space minus space straight h right parenthesis space plus space 1 half left parenthesis space straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis close square brackets
    equals space Lt with straight h rightwards arrow 0 below open square brackets 8 left parenthesis 1 right parenthesis space plus space 3 space left parenthesis 1 right parenthesis space plus space left parenthesis 1 minus straight h right parenthesis space plus space 5 over 2 left parenthesis 1 right parenthesis space left parenthesis 1 minus straight h right parenthesis space plus 1 half left parenthesis 1 minus straight h right parenthesis space left parenthesis 1 right parenthesis space left parenthesis 2 minus straight h right parenthesis close square brackets
                                                                                                           open square brackets because space space straight n space straight h space equals space 2 minus 1 space equals space 1 close square brackets
     = 8 plus 3 space left parenthesis 1 minus 0 right parenthesis space plus space 5 over 2 left parenthesis 1 minus 0 right parenthesis space plus space 1 half left parenthesis 1 minus 0 right parenthesis space left parenthesis 2 minus 0 right parenthesis space equals space 8 plus 3 plus 5 over 2 plus 1 space equals space 29 over 2

    Question 10
    CBSEENMA12032352

    Evaluate integral subscript 1 superscript 3 space left parenthesis 3 straight x squared plus 2 straight x right parenthesis space dx as the limit of sums.

    Solution

    Comparing integral subscript 1 superscript 3 space left parenthesis 3 straight x squared plus 2 straight x right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space space we space get comma
                         straight f left parenthesis straight x right parenthesis space equals space 3 straight x squared plus 2 straight x comma space space straight a space equals space 1 comma space space straight b space equals space 3
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 3 plus 2
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space 3 left parenthesis 1 plus straight h right parenthesis squared plus 2 left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space 3 left parenthesis 1 plus 2 straight h right parenthesis squared plus 2 left parenthesis 1 plus 2 straight h right parenthesis
                  .......................................................................
              straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space 3 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus 2 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now,     integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight f left parenthesis straight a right parenthesis space plus space straight f left parenthesis straight a plus straight h right parenthesis space plus space straight f left parenthesis straight a plus 2 straight h right parenthesis plus..... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis space straight h close square brackets
            equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket space open curly brackets 3 plus 2 right curly bracket plus left curly bracket 3 space left parenthesis 1 plus straight h right parenthesis squared plus 2 space left parenthesis 1 plus straight h right parenthesis right curly bracket plus left curly bracket 3 space left parenthesis 1 plus 2 straight h right parenthesis squared plus 2 space left parenthesis 1 plus 2 straight h right parenthesis close curly brackets
space
                                                                plus.... plus space left curly bracket 3 space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared space plus space 2 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right curly bracket right square bracket
             equals space Lt with straight h rightwards arrow 0 below space left square bracket 3 straight n plus 2 straight n plus 6 straight h space left curly bracket 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right curly bracket space plus space 2 straight h space left curly bracket 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right curly bracket
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space plus space 3 space straight h squared space open curly brackets 1 squared plus 2 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets right square bracket
            equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 5 space straight n plus 6 space straight h space fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n over denominator 2 end fraction plus 2 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus 3 space straight h squared space fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
            equals space Lt with straight h rightwards arrow 0 below space open square brackets 5 space straight n space straight h space plus space 3 space left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis space straight n space straight h right parenthesis plus space 1 half left parenthesis straight n space straight h minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis close square brackets
             equals space Lt with straight h rightwards arrow 0 below open square brackets 5 cross times 2 plus 3 space left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space plus left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space plus space 1 half left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 4 minus straight h right parenthesis close square brackets
                                                                            open square brackets because space straight n space straight h space equals space straight b space minus straight a space equals space 3 space minus space 1 space equals space 2 close square brackets
             equals space 10 plus 6 space left parenthesis 2 minus 0 right parenthesis space plus space 2 left parenthesis 2 minus 0 right parenthesis space plus left parenthesis 2 minus 0 right parenthesis space left parenthesis 4 minus 0 right parenthesis
equals space 10 plus 12 plus 4 plus 8 space equals space 34
                                     

    Question 11
    CBSEENMA12032353

    Evaluate integral subscript 0 superscript 2 left parenthesis straight x squared plus straight x plus 2 right parenthesis space dx as the limit of a sum.

    Solution

    Comparing integral subscript 0 superscript 2 left parenthesis straight x squared plus straight x plus 2 right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                           straight f left parenthesis straight x right parenthesis space equals space straight x squared plus straight x plus 2 comma space space straight a space equals space 0 comma space space straight b space equals space 2
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space 0 plus 0 plus 2 space equals space 2
straight f left parenthesis straight a plus straight b right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight h squared plus straight h plus 2
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 2 straight h right parenthesis space equals space 2 squared straight h squared plus 2 straight h plus 2
                         .............................................................
                            straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis straight n minus 1 right parenthesis squared straight h squared plus left parenthesis straight n minus 1 right parenthesis space straight h space plus 2
    Now,         integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
    therefore            integral subscript 0 superscript 2 left parenthesis straight x squared plus straight x plus 2 right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 2 plus left parenthesis straight h squared plus straight h plus 2 right parenthesis plus left parenthesis 2 squared straight h squared plus 2 straight h plus 2 right parenthesis plus......
                                                                          plus open curly brackets left parenthesis straight n minus 1 right parenthesis squared space straight h squared plus left parenthesis straight n minus 1 right parenthesis space straight h space plus space 2 close curly brackets right square bracket
                            equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 2 space straight n space plus space straight h space left parenthesis 1 plus 2 plus..... plus stack straight n minus 1 with bar on top right parenthesis space plus space straight h squared space open curly brackets 1 squared plus 2 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets close square brackets
                            equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 2 space straight n space space plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis left parenthesis straight n right parenthesis left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets 2 space straight n space straight h space plus space fraction numerator left parenthesis space straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus straight h right parenthesis over denominator 2 end fraction plus fraction numerator left parenthesis space straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus straight h right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets 4 plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis over denominator 2 end fraction plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis space left parenthesis 4 minus straight h right parenthesis over denominator 6 end fraction close square brackets
                                                                                 open square brackets because space space straight n space straight h space equals space straight b minus straight a space equals space 2 minus 0 space equals space 2 close square brackets
                                        equals space 4 plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus 0 right parenthesis over denominator 2 end fraction plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus 0 right parenthesis space left parenthesis 4 minus 0 right parenthesis over denominator 6 end fraction
equals space 4 plus 2 plus 8 over 3 space equals fraction numerator 12 plus 6 plus 8 over denominator 3 end fraction space equals 26 over 3

    Question 12
    CBSEENMA12032354

    Evaluate integral subscript 0 superscript 2 left parenthesis straight x squared plus straight x plus 1 right parenthesis space dx as the limit of a sum.

    Solution

    Comparing integral subscript 0 superscript 2 left parenthesis straight x squared plus straight x plus 1 right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we get
                            straight f left parenthesis straight x right parenthesis space equals space straight x squared plus straight x plus 1 comma space space straight a space equals space 0 comma space space space straight b space equals space 2
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space 0 plus 0 plus 1 space equals space 1
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight h squared plus straight h plus 1 space equals space 1
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 2 straight h right parenthesis space equals space 2 squared straight h squared plus 2 straight h plus 1
                            ...................................................
                         straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top straight h right parenthesis space equals space left parenthesis straight n minus 1 right parenthesis squared space straight h squared space plus space left parenthesis straight n minus 1 right parenthesis space straight h space plus 1
    Now,       integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h left right arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
    therefore            integral subscript 0 superscript 2 space left parenthesis straight x squared plus straight x plus 1 right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 1 plus left parenthesis straight h squared plus straight h plus 1 right parenthesis plus left parenthesis 2 squared straight h squared plus 2 straight h plus 1 right parenthesis plus......
                                                                                   plus open curly brackets left parenthesis straight n minus 1 right parenthesis squared space straight h squared space plus space left parenthesis straight n minus 1 right parenthesis space straight h space plus 1 close curly brackets right square bracket
                          equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight n plus straight h space left parenthesis 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right parenthesis space plus space straight h squared space open curly brackets 1 squared plus 2 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets right square bracket
                           equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight n plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis thin space left parenthesis straight n right parenthesis over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis left parenthesis straight n right parenthesis left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets straight n space straight h space plus space fraction numerator left parenthesis straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus space straight h right parenthesis over denominator 2 end fraction plus fraction numerator left parenthesis space straight n space straight h right parenthesis space left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets 2 plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis over denominator 2 end fraction plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis space left parenthesis 4 minus straight h right parenthesis over denominator 6 end fraction close square brackets
                                                                       open square brackets because space straight n space straight h space equals space straight b space minus straight a space equals space 2 space minus space 0 space equals space 2 close square brackets
                             equals space 2 plus fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus 0 right parenthesis over denominator 2 end fraction plus fraction numerator left parenthesis 2 right parenthesis thin space left parenthesis 2 minus 0 right parenthesis space left parenthesis 4 minus 0 right parenthesis over denominator 6 end fraction
equals space 2 plus 2 plus 8 over 3 space equals space fraction numerator 6 plus 6 plus 8 over denominator 3 end fraction space equals space 20 over 3

    Question 13
    CBSEENMA12032355

    Evaluate  integral subscript 1 superscript 3 left parenthesis straight x squared plus straight x right parenthesis space dx as the limit of sums. 

    Solution

    Comparing integral subscript 1 superscript 3 left parenthesis straight x squared plus straight x right parenthesis space dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                        straight f left parenthesis straight x right parenthesis space equals space straight x squared plus straight x comma space space straight a space equals space 1 comma space space space straight b space equals space 3
    therefore                                  straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 1 plus 1
                           straight f left parenthesis straight a plus straight h right parenthesis space space equals straight f left parenthesis 1 plus straight h right parenthesis space equals space left parenthesis 1 plus straight h right parenthesis squared plus left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals left parenthesis 1 plus 2 straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis
                      ...........................................................................
                          straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h squared right parenthesis space plus space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now,          integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket
    therefore          integral subscript 1 superscript 3 left parenthesis straight x squared plus straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket space left curly bracket 1 plus 1 right curly bracket space plus space left curly bracket left parenthesis 1 plus straight h right parenthesis squared plus left parenthesis 1 plus straight h right parenthesis right curly bracket space plus space left curly bracket left parenthesis 1 plus 2 straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis right curly bracket plus...
                                                                                     .... plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                   equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight n plus 2 straight h space left curly bracket 1 plus 2 plus 3 plus..... plus stack straight n minus 1 with bar on top space right curly bracket space plus space straight h squared space left curly bracket 1 squared plus 2 squared plus 3 squared plus.......
                                                                          plus left parenthesis straight n minus 1 right parenthesis squared right curly bracket plus straight n plus straight h space left curly bracket 1 plus 2 plus 3 plus..... plus stack straight n minus 1 with bar on top right curly bracket right square bracket
                  equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets straight n plus 2 straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction plus straight n plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets straight n space straight h space plus space left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space fraction numerator left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus straight h right parenthesis over denominator 6 end fraction plus space straight n space straight h plus fraction numerator left parenthesis nh space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis over denominator 2 end fraction close square brackets
                 equals space Lt with straight h rightwards arrow 0 below space open square brackets 2 plus left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space plus space fraction numerator left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 4 minus straight h right parenthesis over denominator 6 end fraction plus 2 plus fraction numerator left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis over denominator 2 end fraction close square brackets
                                                                                                 space open square brackets because space space straight n space straight h space space equals space straight b space minus straight a space equals space 3 space minus space 1 space equals space 2 close square brackets
                    equals 2 plus left parenthesis 2 minus 0 right parenthesis left parenthesis 2 right parenthesis plus fraction numerator left parenthesis 2 minus 0 right parenthesis left parenthesis 2 right parenthesis left parenthesis 4 minus 0 right parenthesis over denominator 6 end fraction plus 2 plus fraction numerator left parenthesis 2 minus 0 right parenthesis left parenthesis 2 right parenthesis over denominator 2 end fraction
equals space 2 plus 4 plus 8 over 3 plus 2 plus 2 space equals space 38 over 3

    Question 14
    CBSEENMA12032356

    Evaluate integral subscript 1 superscript 2 left parenthesis straight x squared plus straight x right parenthesis dx as the limit of a sum.

    Solution

    Comparing integral subscript 1 superscript 2 left parenthesis straight x squared plus straight x right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we get,
              straight f left parenthesis straight x right parenthesis space equals space straight x squared plus straight x comma space space straight a space equals space 1 comma space space straight b space equals space 2
    therefore                   straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals 1 plus 1
                       straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals left parenthesis 1 plus straight h right parenthesis squared plus left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space left parenthesis 1 plus 2 straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis
    ............................................................................
            straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    therefore   integral subscript 1 superscript 2 left parenthesis straight x squared plus straight x right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket left curly bracket 1 plus 1 right curly bracket plus left curly bracket left parenthesis 1 plus straight h right parenthesis squared plus left parenthesis 1 plus straight h right parenthesis right curly bracket plus left curly bracket left parenthesis 1 plus 2 straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis right curly bracket plus.....  
                                                                                   ... plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                                   equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight n plus 2 straight h space left curly bracket 1 plus 2 plus 3 plus....... plus stack straight n minus 1 with bar on top right curly bracket space plus space straight h squared left curly bracket 1 squared plus 2 squared plus 3 squared plus.....    
                                                                    plus left parenthesis straight n minus 1 right parenthesis squared right curly bracket plus straight n plus straight h space left curly bracket 1 plus 2 plus 3 plus.... plus stack straight n minus 1 with bar on top right curly bracket right square bracket
                                   equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets straight n plus 2 straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction plus straight n plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis left parenthesis straight n right parenthesis over denominator 2 end fraction close square brackets
                                     equals space Lt with straight h rightwards arrow 0 below space open square brackets straight n space straight h plus left parenthesis nh minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space fraction numerator left parenthesis space straight n space straight h space minus space straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis over denominator 6 end fraction plus space straight n space straight h space plus fraction numerator left parenthesis space nh space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets 1 plus left parenthesis 1 minus straight h right parenthesis space left parenthesis 1 right parenthesis plus fraction numerator left parenthesis 1 minus straight h right parenthesis space left parenthesis 1 right parenthesis space left parenthesis 2 minus straight h right parenthesis over denominator 6 end fraction plus 1 plus fraction numerator left parenthesis 1 minus straight h right parenthesis space left parenthesis 1 right parenthesis over denominator 2 end fraction close square brackets
                                                                                                           open square brackets because space straight n space straight h space equals space straight b minus straight a space equals space 2 minus 1 space equals space 1 close square brackets
                                     equals 1 plus left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis space plus space fraction numerator left parenthesis 1 minus 0 right parenthesis left parenthesis 1 right parenthesis space left parenthesis 2 minus 0 right parenthesis over denominator 6 end fraction plus 1 plus fraction numerator left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis over denominator 2 end fraction
equals space 1 plus 1 plus 1 third plus 1 plus 1 half space equals 23 over 3

    Question 15
    CBSEENMA12032357

    Evaluate integral subscript 0 superscript 2 left parenthesis straight x squared plus straight x right parenthesis space dx as the limit of sum.

    Solution

    Comparing integral subscript 1 superscript 2 left parenthesis straight x squared plus straight x right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space space we space get
                         straight f left parenthesis straight x right parenthesis space equals space straight x squared plus straight x comma space space straight a space equals space 1 comma space space straight b space equals space 2
    therefore                    f(a) = f(1) = 1+1
                          straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space left parenthesis 1 plus straight h right parenthesis squared plus left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space left parenthesis 1 plus 2 straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis
                         ................................................................................
                      straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared space plus space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now          integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    therefore space space space integral subscript 1 superscript 2 left parenthesis straight x squared plus straight x right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below left square bracket left curly bracket 1 plus 1 right curly bracket space plus space left curly bracket left parenthesis 1 plus straight h right parenthesis right curly bracket space plus left curly bracket left parenthesis 1 plus 2 straight h right parenthesis squared plus left parenthesis 1 plus 2 straight h right parenthesis right curly bracket plus.....
                                                                                    ..... plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                                  equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight n plus 2 straight h fraction numerator left parenthesis straight n minus 1 right parenthesis straight n over denominator 2 end fraction plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis thin space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction plus straight n plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets straight n space straight h plus left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space fraction numerator left parenthesis straight n space straight h minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h minus straight h right parenthesis over denominator 6 end fraction plus space straight n space straight h space plus space fraction numerator left parenthesis space straight n space straight h space minus space straight h right parenthesis space left parenthesis straight n space straight h right parenthesis over denominator 2 end fraction close square brackets
                                 equals space Lt with straight h rightwards arrow 0 below open square brackets 1 plus left parenthesis 1 minus straight h right parenthesis left parenthesis 1 right parenthesis plus fraction numerator left parenthesis 1 minus straight h right parenthesis left parenthesis 1 right parenthesis left parenthesis 2 minus straight h right parenthesis over denominator 6 end fraction plus 1 plus fraction numerator left parenthesis 1 minus straight h right parenthesis left parenthesis 1 right parenthesis over denominator 2 end fraction close square brackets
                                                                                                         open square brackets because space straight n space straight h space equals space straight b minus straight a space equals space 2 minus 1 space equals space 1 close square brackets
                                 equals 1 plus left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis space plus space fraction numerator left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis thin space left parenthesis 2 minus 0 right parenthesis over denominator 6 end fraction plus 1 plus fraction numerator left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis over denominator 2 end fraction
equals space 1 plus 1 plus 1 third plus 1 plus 1 half space equals 23 over 3

    Question 16
    CBSEENMA12032358

    Evaluate as limit of sums integral subscript 1 superscript 4 left parenthesis 5 straight x squared plus 3 straight x right parenthesis space dx.

    Solution

    Comparing integral subscript 1 superscript 4 space left parenthesis 5 straight x squared plus 3 straight x right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space space we space get
                             space straight f left parenthesis straight x right parenthesis space equals space 5 straight x squared plus 3 straight x comma space space space straight a space equals space 1 comma space space space straight b space equals space 4
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 5 plus 3
straight f left parenthesis straight a plus straight b right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space 5 left parenthesis 1 plus straight h right parenthesis squared plus 3 left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space 5 left parenthesis 1 plus 2 straight h right parenthesis squared plus 3 left parenthesis 1 plus 2 straight h right parenthesis
    ............................................................................
                           straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space 5 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared space plus space 3 left parenthesis 1 plus stack straight n minus 1 with bar on top straight h right parenthesis
    Now,                integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis straight h right square bracket
                         equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket left curly bracket 5 plus 3 right curly bracket space plus space left curly bracket 5 space left parenthesis 1 plus straight h right parenthesis squared plus 3 left parenthesis 1 plus straight h right parenthesis right curly bracket space plus space left curly bracket 5 left parenthesis 1 plus 2 straight h right parenthesis squared plus 3 left parenthesis 1 plus 2 straight h right parenthesis right curly bracket
                                                                                plus........... plus left curly bracket 5 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus 3 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right curly bracket right square bracket
                        equals Lt with straight h rightwards arrow 0 below space straight h space left square bracket 5 straight n space plus 3 straight n plus 10 space straight h space left curly bracket 1 plus 2 plus... plus stack straight n minus 1 with bar on top right curly bracket space plus space 3 space straight h space left curly bracket 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right curly bracket
                                                                                             plus space 5 space straight h squared space left curly bracket 1 squared plus 2 squared plus..... open parentheses stack straight n minus 1 with bar on top close parentheses squared right curly bracket right square bracket
                      space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets space 8 space straight n space plus space 10 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus 3 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus fraction numerator 5 space straight h squared space left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
equals space space Lt with straight h rightwards arrow 0 below space open square brackets 8 space straight n space straight h space plus space 5 space left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space 3 over 2 left parenthesis space straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space 5 over 6 left parenthesis space straight n space straight h space minus space straight h right parenthesis space left parenthesis space straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis close square brackets
                      equals space Lt with straight h rightwards arrow 0 below space open square brackets 8 plus 3 plus 5 left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis space plus space 3 over 2 left parenthesis 3 minus straight h right parenthesis thin space left parenthesis 3 right parenthesis space plus space 5 over 6 left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis space left parenthesis 6 minus straight h right parenthesis close square brackets
                                                                                            open square brackets because space straight n space straight h space equals space straight b space minus straight a space equals space 4 minus 1 space equals 3 close square brackets
                      equals space 24 plus 15 left parenthesis 3 minus 0 right parenthesis space plus space 9 over 2 left parenthesis 3 minus 0 right parenthesis space plus space 5 over 2 left parenthesis 3 minus 0 right parenthesis space left parenthesis 6 minus 0 right parenthesis
equals space 24 plus 45 plus 27 over 2 plus 45 space equals space 114 plus 27 over 2 space equals space 255 over 2
                     


    Question 17
    CBSEENMA12032359

    Evaluate as limit of sums integral subscript 1 superscript 4 left parenthesis 3 straight x squared plus 2 straight x right parenthesis space dx.

    Solution

    Comparing  integral subscript 1 superscript 4 left parenthesis 3 straight x squared plus 2 straight x right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                       straight f left parenthesis straight x right parenthesis space equals space 3 straight x squared plus 2 straight x comma space space space straight a space equals space 1 comma space space straight b space equals space 4
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 3 space plus space 2
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space 3 left parenthesis 1 plus straight h right parenthesis squared plus 2 left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals space 3 left parenthesis 1 plus 2 straight h right parenthesis squared plus 2 left parenthesis 1 plus 2 straight h right parenthesis
                           .............................................................
                             straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space 3 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus 2 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now,    integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus top enclose straight n minus 1 end enclose right parenthesis straight h close square brackets
                   equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket space left curly bracket 3 plus 2 right curly bracket plus left curly bracket 3 left parenthesis 1 plus straight h right parenthesis squared plus 2 left parenthesis 1 plus straight h right parenthesis right curly bracket space plus space left curly bracket 3 space left parenthesis 1 plus 2 straight h right parenthesis squared plus 2 left parenthesis 1 plus 2 straight h right parenthesis right curly bracket
                                                                        plus..... plus left curly bracket 3 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared space plus space 2 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right curly bracket right square bracket
                    equals space Lt with straight h rightwards arrow 0 below left square bracket 3 space straight n space plus space 2 space straight n space plus space 6 space straight h space left curly bracket 1 plus 2 plus..... plus stack straight n minus 1 with bar on top right curly bracket space plus space 2 straight h left curly bracket 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right curly bracket
                                                                              plus 3 straight h squared left curly bracket 1 squared plus 2 squared plus..... left parenthesis stack straight n minus 1 with bar on top right parenthesis squared right curly bracket right square bracket
                     equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets 5 straight n space plus 6 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis straight n over denominator 2 end fraction plus 2 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus 3 straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets space
equals space Lt with straight h rightwards arrow 0 below space open square brackets 5 space straight n space straight h space plus space 3 space left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis straight n space straight h space right parenthesis plus 1 half left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis space straight n space straight h right parenthesis space left parenthesis 2 space straight n space straight h space minus space straight h right parenthesis close square brackets
                      equals space Lt with straight h rightwards arrow 0 below space open square brackets 5 cross times 3 plus 3 space left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis space plus space left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis space plus space 1 half left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis space left parenthesis 6 minus straight h right parenthesis close square brackets
                                                                                          space space space space open square brackets because space space straight n space straight h space equals space straight b space minus space straight a space equals space 4 space minus space 1 space equals space 3 close square brackets
                    equals space 15 plus 9 space left parenthesis 3 minus 0 right parenthesis plus 3 space left parenthesis 3 minus 0 right parenthesis space left parenthesis 2 right parenthesis space plus space 3 over 2 left parenthesis 3 minus 0 right parenthesis space left parenthesis 6 minus 0 right parenthesis
space equals space 15 plus 27 plus 9 plus 27 space equals space 78

    Sponsor Area

    Question 18
    CBSEENMA12032360

    Evaluate as limit of sums: integral subscript 1 superscript 3 left parenthesis 2 straight x squared plus 3 straight x right parenthesis space dx. space

    Solution

    Comparing integral subscript 1 superscript 3 left parenthesis 2 straight x squared plus 3 straight x right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                        straight f left parenthesis straight x right parenthesis space equals space 2 straight x squared plus 3 straight x comma space space straight a space equals space 1 comma space space space straight b space equals space 3
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 1 right parenthesis space equals space 2 space plus 3
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 1 plus straight h right parenthesis space equals space 2 left parenthesis 1 plus straight h right parenthesis squared plus 3 left parenthesis 1 plus straight h right parenthesis
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 1 plus 2 straight h right parenthesis space equals 2 left parenthesis 1 plus 2 straight h right parenthesis squared plus 3 left parenthesis 1 plus 2 straight h right parenthesis
                        .................................................................
                                straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space 2 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared plus 3 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis
    Now,           integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus top enclose straight n minus 1 end enclose right parenthesis space straight h right parenthesis close square brackets
        equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket open curly brackets 2 plus 3 close curly brackets space plus space left curly bracket 2 space left parenthesis 1 plus straight h right parenthesis squared space plus space 3 space left parenthesis 1 plus straight h right parenthesis right curly bracket space plus space left curly bracket 2 left parenthesis 1 plus 2 straight h right parenthesis squared plus 3 left parenthesis 1 plus 2 straight h right parenthesis space right curly bracket      
                                                                          plus.... plus left curly bracket 2 left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis squared space plus space 3 space left parenthesis 1 plus stack straight n minus 1 with bar on top space straight h right parenthesis right curly bracket right square bracket
          equals space Lt with straight h rightwards arrow 0 below left square bracket 2 space straight n space plus space 3 space straight n space plus space 4 space straight h space left square bracket 1 plus 2 plus........ plus stack straight n minus 1 with bar on top right curly bracket space plus space 3 space straight h space left curly bracket 1 plus 2 plus.... plus stack straight n minus 1 with bar on top right curly bracket
                                                                                        plus 2 space straight h squared space left curly bracket 1 squared plus 2 squared plus......... left parenthesis stack straight n minus 1 with bar on top right parenthesis squared right curly bracket right square bracket
          space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets 5 space straight n plus space 4 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n over denominator 2 end fraction plus 3 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus 2 space straight h squared space fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below space open square brackets 5 space straight n space straight h space plus space 2 space left parenthesis space straight n space straight h space minus straight h right parenthesis space left parenthesis space straight n space straight h right parenthesis space plus space 3 over 2 left parenthesis straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space 1 third left parenthesis space straight n space straight h space minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis thin space left parenthesis 2 space straight n space straight h space minus straight h right parenthesis close square brackets
          equals space Lt with straight h rightwards arrow 0 below space open square brackets 5 cross times 2 plus 2 left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space plus space 3 over 2 left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space plus space 1 third left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 4 minus straight h right parenthesis close square brackets
                                                                                                          left square bracket because space straight n space straight h space equals space space straight b space minus space straight a space equals space 3 space minus space 1 space equals space 2 space right square bracket
           equals 10 plus 4 space left parenthesis 2 minus 0 right parenthesis space plus space 3 over 2 left parenthesis 2 minus 0 right parenthesis space left parenthesis 2 right parenthesis space plus 1 third left parenthesis 2 minus 0 right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 4 minus 0 right parenthesis
equals space 10 plus 8 plus 6 plus 16 over 3 space equals space 88 over 3
           

    Question 19
    CBSEENMA12032361

    Evaluate the following integral as limit of a sum
    integral subscript 0 superscript 2 left parenthesis straight x squared plus 3 right parenthesis space dx.

    Solution

    Comparing integral subscript 0 superscript 2 left parenthesis straight x squared plus 3 right parenthesis space dx space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma we get,
                        straight f left parenthesis straight x right parenthesis space equals space straight x squared plus 3 comma space space straight a space equals space 0 comma space space straight b space equals space 2
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space 0 plus 3 space equals space 3
               straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 0 plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight h squared plus 3
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 0 plus 2 straight h right parenthesis space equals space straight f left parenthesis 2 straight h right parenthesis space equals space 2 squared. space straight h squared plus 3
....... space space space space space space space space space space space space...... space space space space space space space space space space space...... space space space space space space space space space.....
          straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis straight n minus 1 right parenthesis squared space straight h squared space plus space 3
    Now   integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis space plus space straight f left parenthesis straight a plus straight h right parenthesis space plus space straight f left parenthesis straight a plus 2 straight h right parenthesis space plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis
    therefore      integral subscript 0 superscript 2 left parenthesis straight x squared plus 3 right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 3 plus open curly brackets straight h squared plus 3 close curly brackets space plus open curly brackets 2 squared. space straight h squared space plus space 3 close curly brackets space plus space................
                                                                                                plus space open curly brackets left parenthesis straight n minus 1 right parenthesis squared. space straight h squared space plus space 3 close curly brackets right square bracket
                                     equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets 3 space straight n space plus space straight h squared space open curly brackets 1 squared plus 2 squared plus 3 squared plus..... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets close square brackets
equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets 3 space straight n space plus space straight h squared. space fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
space equals space Lt with straight h rightwards arrow 0 below open square brackets 3 left parenthesis straight n space straight h right parenthesis space plus space fraction numerator left parenthesis straight n space straight h right parenthesis space left parenthesis nh space minus straight h right parenthesis space left parenthesis space 2 space straight n space straight h space minus space straight h right parenthesis over denominator 6 end fraction close square brackets
                                 equals space Lt with straight h space rightwards arrow 0 below space open square brackets 3 space left parenthesis 2 space right parenthesis plus space fraction numerator left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis space left parenthesis 4 minus straight h right parenthesis over denominator 6 end fraction close square brackets space space space space left square bracket because space space straight n space straight h space equals space straight b minus straight a space equals space 2 minus 0 space equals space 2 right square bracket
                               equals space 3 left parenthesis 2 right parenthesis plus fraction numerator left parenthesis 2 right parenthesis thin space left parenthesis 2 minus 0 right parenthesis space left parenthesis 4 minus 0 right parenthesis over denominator 6 end fraction space equals space 6 plus 8 over 3 space equals space 26 over 3

    Question 20
    CBSEENMA12032362

    Evaluate the following integrals as the limit of a sum
    integral subscript 0 superscript 2 left parenthesis straight x squared plus 1 right parenthesis space dx

    Solution

    Comparing integral subscript 0 superscript 2 left parenthesis straight x squared plus 1 right parenthesis space dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                       straight f left parenthesis straight x right parenthesis space equals straight x squared plus 1 semicolon space space space straight a space equals space 0 comma space space straight b equals space 2
    therefore              straight f left parenthesis straight a right parenthesis space equals space straight a squared plus 1 comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space left parenthesis straight a plus straight h right parenthesis squared plus 1 comma space space straight f left parenthesis straight a plus 2 straight h right parenthesis space space equals left parenthesis straight a plus 2 straight h right parenthesis squared plus 1 comma
                       .......,   straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left square bracket straight a plus left parenthesis straight n minus 1 right parenthesis space straight h squared right square bracket space plus space 1
    Now,       integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    rightwards double arrow          integral subscript straight a superscript straight b left parenthesis straight x squared plus 1 right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket left curly bracket straight a squared plus 1 right curly bracket space plus space left curly bracket left parenthesis straight a plus straight h right parenthesis squared plus 1 right curly bracket space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space
                                                                       plus open curly brackets left parenthesis straight a plus 2 straight h right parenthesis squared plus 1 close curly brackets plus.... plus open curly brackets left parenthesis straight a plus stack straight n minus 1 with bar on top straight h squared right parenthesis plus 1 close curly brackets right square bracket
                  equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets left parenthesis straight a squared plus straight a squared plus straight a squared plus..... space to space straight n space terms right parenthesis plus space open curly brackets 1 plus 1 plus 1 plus.... plus space to space straight n space terms close curly brackets close square brackets
space space space plus space straight h squared space open curly brackets 1 squared plus 2 cubed plus 3 squared plus..... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets space plus space 2 ah open curly brackets 1 plus 2 plus 3 plus.... plus left parenthesis straight n minus 1 right parenthesis close curly brackets right square bracket
                   equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight n space straight a squared plus straight n plus straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction plus 2 space straight a space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space straight n over denominator 2 end fraction close square brackets
                 equals space Lt with straight h rightwards arrow 0 below open square brackets straight a squared left parenthesis nh right parenthesis space plus nh plus fraction numerator left parenthesis nh minus straight h right parenthesis thin space left parenthesis nh right parenthesis space left parenthesis 2 nh minus straight h right parenthesis over denominator 6 end fraction plus straight a left parenthesis nh right parenthesis space left parenthesis nh minus straight h right parenthesis close square brackets space
equals stack space Lt with straight h rightwards arrow 0 below open square brackets 0 space left parenthesis 2 right parenthesis plus 2 space plus space fraction numerator left parenthesis 2 minus straight h right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 4 minus straight h right parenthesis over denominator 6 end fraction plus left parenthesis 0 right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 2 minus straight h right parenthesis close square brackets
                                                                                           left square bracket because space nh space equals space straight b minus straight a space equals space 2 minus 0 space equals space 2 right square bracket
                equals 0 plus 2 plus fraction numerator left parenthesis 2 minus 0 right parenthesis space left parenthesis 2 right parenthesis space left parenthesis 4 minus 0 right parenthesis over denominator 6 end fraction space equals 0 space equals space 2 plus 8 over 3 space equals space 14 over 3

    Question 21
    CBSEENMA12032363

    Evaluate the following integrals as the limit of a sum
    integral subscript 0 superscript 3 left parenthesis straight x squared plus 2 straight x right parenthesis space dx

    Solution

    Comparing integral subscript 0 superscript 3 left parenthesis straight x squared plus 2 straight x right parenthesis space dx with integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx
           straight f left parenthesis straight x right parenthesis space equals space straight x squared plus 2 straight x comma space space space space straight a space equals space 0 comma space space straight b space equals space 3
         straight f left parenthesis straight a right parenthesis space equals space 0
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight h squared plus 2 straight h
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 2 straight h right parenthesis space equals space 2 squared straight h squared plus 2. space 2 straight h
    ........   ............. ..........         ...........          ........
            
    Now  integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight x rightwards arrow 0 below space straight h space open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight a left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis close square brackets
    therefore     integral subscript 0 superscript 3 left parenthesis straight x squared plus 2 straight x right parenthesis dx space equals space Lt with straight h rightwards arrow 0 below straight h left square bracket 0 plus left parenthesis straight h squared plus 2 straight h right parenthesis plus left parenthesis 2 squared. straight h squared space plus 2. space 2 straight h right parenthesis
                                                                   plus left parenthesis 3 squared. straight h squared plus 3. space 2 straight h right parenthesis plus open curly brackets left parenthesis straight n minus 1 right parenthesis squared. space straight h squared plus left parenthesis straight n minus 1 right parenthesis. space 2 straight h close curly brackets]
               equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets open curly brackets 1 squared plus 2 squared plus 3 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared close curly brackets space straight h squared plus space open curly brackets 1 plus 2 plus 3 plus.. plus left parenthesis straight n minus 1 right parenthesis close curly brackets. space 2 straight h close square brackets
               equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction. space straight h squared plus space fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction. space 2 straight h close square brackets
              equals Lt with straight h rightwards arrow 0 below open square brackets fraction numerator left parenthesis straight n minus straight h right parenthesis space left parenthesis nh right parenthesis space left parenthesis 2 nh minus straight h right parenthesis over denominator 6 end fraction plus left parenthesis nh minus straight h right parenthesis space left parenthesis nh right parenthesis close square brackets
            equals space Lt with straight h rightwards arrow 0 below open square brackets fraction numerator left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis space left parenthesis 6 minus straight h right parenthesis over denominator 6 end fraction plus left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis close square brackets                                     open square brackets because space space nh space equals space straight b minus straight a space equals 3 minus 0 space equals space 3 close square brackets
              equals space fraction numerator left parenthesis 3 minus 0 right parenthesis space left parenthesis 3 right parenthesis space left parenthesis 6 minus 0 right parenthesis over denominator 6 end fraction plus left parenthesis 3 minus 0 right parenthesis space left parenthesis 3 right parenthesis space equals space 9 plus 9 space equals space 18

    Question 22
    CBSEENMA12032364

    Evaluate the following integrals as the limit of a sum
    integral subscript 0 superscript 3 left parenthesis 2 straight x squared plus 3 right parenthesis space dx

    Solution

    Comparing integral subscript 0 superscript 3 left parenthesis 2 straight x squared plus 3 right parenthesis space dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get comma
                      straight f left parenthesis straight x right parenthesis space equals space 2 straight x squared plus 3 comma space space space space space straight a space equals space 0 comma space space space straight b space equals space 3
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space 0 plus 3 space equals space 3
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space 2 straight h squared plus 3
                    straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 2 straight h right parenthesis space space equals space 2. space 2 squared space straight h squared plus 3
    .........        ...........        ...........        ..........        ..........          .............
    straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis space equals space 2. left parenthesis straight n minus 1 right parenthesis squared straight h squared plus 3
    Now,         
                                 integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis space plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus top enclose straight n minus 1 end enclose space straight h right parenthesis close square brackets
space space space space space space space space space space space space space space space space space space equals space stack Lt space straight h with straight h rightwards arrow 0 below space open square brackets 3 plus left parenthesis 2 straight h squared plus 3 right parenthesis plus left parenthesis 2.2 squared straight h squared plus 3 right parenthesis plus..... plus open curly brackets 2 left parenthesis straight n minus 1 right parenthesis squared space straight h squared plus 3 close curly brackets close square brackets
space space space space space space space space space space space space space space space space space space space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 3 straight n plus 2 straight h squared left curly bracket 1 squared plus 2 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared right curly bracket close square brackets
space space space space space space space space space space space space space space space space space space equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets 3 straight n plus 2 straight h squared space fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis space left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction close square brackets
space space space space space space space space space space space space space space space space space space equals Lt with straight h rightwards arrow 0 below space open square brackets 3 space nh space plus space fraction numerator left parenthesis straight n minus straight h right parenthesis space left parenthesis nh right parenthesis space left parenthesis 2 nh minus straight h right parenthesis over denominator 3 end fraction close square brackets
                                             equals space Lt with straight h rightwards arrow 0 below space open square brackets 3 left parenthesis 3 right parenthesis space plus space fraction numerator left parenthesis 3 minus straight h right parenthesis space left parenthesis 3 right parenthesis thin space left parenthesis 6 minus straight h right parenthesis over denominator 3 end fraction close square brackets space space space space space left square bracket because space straight n space straight h space equals space straight b minus straight a space equals space 3 minus 0 space equals space 3 right square bracket
equals space space space 9 plus fraction numerator left parenthesis 3 minus 0 right parenthesis space left parenthesis 3 right parenthesis thin space left parenthesis 6 minus 0 right parenthesis over denominator 3 end fraction space equals space 9 plus 18 space equals space 27

    Question 23
    CBSEENMA12032365

    Evaluate integral subscript 2 superscript 3 space straight x cubed space dx as the limit of a sum.

    Solution

    Comparing integral subscript 2 superscript 3 space straight x cubed space dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get
                             straight f left parenthesis straight x right parenthesis space equals space straight x cubed comma space space straight a space equals space 2 comma space space straight b space equals space 3
straight f left parenthesis straight a right parenthesis space equals space 2 cubed
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis 2 plus 2 space straight h right parenthesis space equals space left parenthesis 2 plus 2 straight h right parenthesis cubed
                          .......................................................
                         straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis space equals space straight f left parenthesis 2 plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space left parenthesis 2 plus stack straight n minus 1 with bar on top space straight h right parenthesis cubed
    Now,      integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis
                                     equals stack space Lt with straight h rightwards arrow 0 below space straight h space left square bracket 2 cubed plus left parenthesis 2 plus straight h right parenthesis cubed plus left parenthesis 2 plus 2 straight h right parenthesis cubed plus.... plus left parenthesis 2 plus stack straight n minus 1 with bar on top space straight h right parenthesis cubed right square bracket
    equals space stack Lt space straight h with straight h rightwards arrow 0 below space left square bracket 2 cubed space cross times space straight n space plus space 12 space straight h space left curly bracket 1 plus 2 plus 3.. plus.... left parenthesis straight n minus 1 right parenthesis right curly bracket space plus space 6 straight h squared space left curly bracket 1 squared plus 2 squared plus 3 squared plus.... plus left parenthesis straight n minus 1 right parenthesis squared right square bracket
                                                                                               plus straight h cubed space left curly bracket 1 cubed plus 2 cubed plus 3 cubed plus... plus left parenthesis straight n minus 1 right parenthesis cubed right curly bracket right square bracket
    equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets 8 space straight n plus 12 space straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus 6 space straight h squared fraction numerator left parenthesis straight n minus 1 right parenthesis left parenthesis straight n right parenthesis left parenthesis 2 straight n minus 1 right parenthesis over denominator 6 end fraction plus straight h cubed fraction numerator left parenthesis straight n minus 1 right parenthesis squared space straight n squared over denominator 4 end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below open square brackets 8 space nh space plus space 6 left parenthesis straight n space straight h space minus space straight h right parenthesis space left parenthesis straight n space straight h right parenthesis space plus space left parenthesis straight n space straight h minus straight h right parenthesis space left parenthesis nh right parenthesis space left parenthesis 2 space straight n space straight h space minus straight h right parenthesis space plus space space fraction numerator left parenthesis nh minus straight h right parenthesis squared space left parenthesis straight n space straight h right parenthesis squared over denominator 4 end fraction close square brackets
    equals space Lt with straight h rightwards arrow 0 below space open square brackets 8 cross times 1 plus 6 left parenthesis 1 minus straight h right parenthesis space left parenthesis 1 right parenthesis space plus space left parenthesis 1 minus straight h right parenthesis space left parenthesis 1 right parenthesis space left parenthesis 2 minus straight h right parenthesis plus fraction numerator left parenthesis 1 minus straight h right parenthesis squared left parenthesis 1 right parenthesis squared over denominator 4 end fraction close square brackets   left square bracket because space straight n space straight h space equals space straight b minus straight a space equals space 3 minus 2 space equals space 1 right square bracket
    equals 8 plus 6 space left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis space plus left parenthesis 1 minus 0 right parenthesis space left parenthesis 1 right parenthesis space left parenthesis 2 minus 0 right parenthesis space plus space fraction numerator left parenthesis 1 minus 0 right parenthesis squared space left parenthesis 1 right parenthesis squared over denominator 4 end fraction space equals space 8 plus 6 plus 2 plus 1 fourth space equals space 65 over 4

    Question 24
    CBSEENMA12032366

    Evaluate
    integral subscript straight a superscript straight b space straight e to the power of straight x space dx as limit of sum. 

    Solution

    Comparing integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space with space integral subscript straight a superscript straight b space straight e to the power of straight x dx comma space space we space get comma
                            straight f left parenthesis straight x right parenthesis space equals space straight e to the power of straight x
    therefore                 straight f left parenthesis straight a right parenthesis space equals space straight e to the power of straight a comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight e to the power of straight a plus straight h end exponent comma
                        straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight e to the power of straight a plus 2 straight h end exponent space space...... space space straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight e to the power of straight a plus left parenthesis straight n minus 1 right parenthesis straight h end exponent
    Now,       integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    rightwards double arrow           integral subscript straight a superscript straight b straight e to the power of straight x dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight e to the power of straight a plus straight e to the power of straight a plus straight h end exponent plus straight e to the power of straight a plus 2 straight h end exponent plus... plus straight e to the power of straight a plus left parenthesis straight n minus 1 right parenthesis straight h end exponent right square bracket
                                    equals space Lt with straight h rightwards arrow 0 below space straight h space straight e to the power of straight a space open square brackets fraction numerator 1 left parenthesis straight e to the power of nh minus 1 end exponent right parenthesis over denominator straight e to the power of straight h minus 1 end exponent end fraction close square brackets                         open square brackets because space space space straight S subscript straight n space equals space straight a fraction numerator left parenthesis straight r to the power of straight n minus 1 right parenthesis over denominator straight r minus 1 end fraction close square brackets
                                    equals space Lt with straight h rightwards arrow 0 below space straight h space straight e to the power of straight a space open square brackets fraction numerator straight e to the power of straight b minus straight a end exponent minus 1 over denominator straight e to the power of straight h minus 1 end fraction close square brackets space space space space space space space space space space space space space space space space space space space space space space space left square bracket because space space nh space equals space straight b minus straight a right square bracket
                                    equals space straight e to the power of straight a space left parenthesis straight e to the power of straight b minus straight a end exponent minus 1 right parenthesis space Lt with straight h rightwards arrow 0 below space open parentheses fraction numerator 1 over denominator begin display style fraction numerator straight e to the power of straight h minus 1 over denominator straight h end fraction end style end fraction close parentheses
                                    equals space left parenthesis straight e to the power of straight b minus straight e to the power of straight a right parenthesis. space 1 over 1 space equals space straight e to the power of straight b space minus space straight e to the power of straight a

    Question 25
    CBSEENMA12032367

    Evaluate integral subscript negative 1 end subscript superscript 1 space straight e to the power of straight x space dx as the limit of a sum.

    Solution

    Comparing  integral subscript negative 1 end subscript superscript 1 space straight e to the power of straight x space dx. space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get comma
                   straight f left parenthesis straight x right parenthesis space equals space straight e to the power of straight x comma space space space straight a space equals space minus 1 comma space space straight b space equals space 1
    therefore space space straight f left parenthesis straight a right parenthesis space equals space straight e to the power of straight a comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight e to the power of straight a plus straight h end exponent comma space space straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight e to the power of straight a plus 2 straight h end exponent comma space space..... comma
           straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight e to the power of straight a plus left parenthesis straight n minus 1 right parenthesis straight h end exponent
    Now integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    therefore       integral subscript negative 1 end subscript superscript 1 space straight e to the power of straight x space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight e to the power of straight a plus straight e to the power of straight a plus straight h end exponent plus straight e to the power of straight a plus 2 straight h end exponent plus.... plus straight e to the power of straight a plus left parenthesis straight n minus 1 right parenthesis space straight h end exponent close square brackets
                                 equals space Lt with straight h rightwards arrow 0 below straight h open square brackets fraction numerator straight e to the power of straight a left parenthesis straight e to the power of straight n space straight h end exponent minus 1 right parenthesis over denominator straight e to the power of straight h minus 1 end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below straight h open square brackets fraction numerator straight e to the power of straight a left parenthesis straight e squared minus 1 right parenthesis over denominator straight e to the power of straight h minus 1 end fraction close square brackets
                                                                                 left square bracket because space space straight n space straight h space equals space straight b space minus space straight a space equals space 1 plus 1 space equals space 2 right square bracket
                                equals straight e to the power of straight a left parenthesis straight e squared minus 1 right parenthesis space Lt with straight h rightwards arrow 0 below fraction numerator straight h over denominator straight e to the power of straight h minus 1 end fraction space equals straight e to the power of straight a left parenthesis straight e squared minus 1 right parenthesis space fraction numerator 1 over denominator begin display style Lt with straight h rightwards arrow 0 below fraction numerator straight e to the power of straight h minus 1 over denominator straight h end fraction end style end fraction
                                    equals space straight e to the power of straight a left parenthesis straight e squared minus 1 right parenthesis. space 1 over 1 space equals space straight e to the power of straight a left parenthesis straight e squared minus 1 right parenthesis space equals space straight e to the power of negative 1 end exponent left parenthesis straight e squared minus 1 right parenthesis space space space space space left square bracket because space straight a space equals space minus 1 right square bracket
equals space straight e minus straight e to the power of negative 1 end exponent space equals space straight e minus 1 over straight e

    Question 26
    CBSEENMA12032368

    Evaluate integral subscript 0 superscript 2 straight e to the power of straight x space dx as the limit of a sum.

    Solution

    Comparing integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space with space integral subscript 0 superscript 2 straight e to the power of straight x space dx comma space we space get comma
                  straight f left parenthesis straight x right parenthesis space equals space straight e to the power of straight x comma space space straight a space equals space 0 comma space space straight b space equals space 2
    therefore          straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space straight e to the power of 0 space equals space 1 comma space space left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight e to the power of straight h comma
                  straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 2 space straight h right parenthesis space equals space straight e to the power of 2 straight h end exponent comma space space.... comma space space straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight e to the power of left parenthesis straight n minus 1 right parenthesis space straight h end exponent
    Now      
     rightwards double arrow space space space integral subscript 0 superscript 2 straight e to the power of straight x space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 1 plus straight e to the power of straight h plus 2 straight e to the power of 2 straight h end exponent plus.... plus straight e to the power of left parenthesis straight n minus 1 right parenthesis straight h end exponent right square bracket
                              equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator 1 left parenthesis straight e to the power of nh minus 1 right parenthesis over denominator straight e to the power of straight h minus 1 end fraction close square brackets space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space straight S subscript straight n space equals space fraction numerator straight a left parenthesis straight r to the power of straight n minus 1 end exponent right parenthesis over denominator straight r minus 1 end fraction close square brackets
                             equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator straight e squared minus 1 over denominator straight e to the power of straight h minus 1 end fraction close square brackets                               open square brackets because space straight n space straight h space equals space straight b minus straight a space equals space 2 minus 0 space equals space 2 close square brackets
                               equals left parenthesis straight e squared minus 1 right parenthesis space fraction numerator 1 over denominator begin display style Lt with straight h rightwards arrow 0 below fraction numerator straight e to the power of straight h minus 1 over denominator straight h end fraction end style end fraction
equals space left parenthesis straight e squared minus 1 right parenthesis space cross times 1 over 1 space equals space straight e squared minus 1

    Question 27
    CBSEENMA12032369

    Evaluate integral subscript 0 superscript 1 straight e to the power of 2 minus 3 straight x end exponent space dx as a limit of a sum.

    Solution

    Comparing integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space with space integral subscript 0 superscript 1 straight e to the power of 2 minus 3 straight x end exponent space dx comma space we get
                    straight f left parenthesis straight x right parenthesis space equals space straight e to the power of 2 minus 3 straight x end exponent comma space space straight a space equals space 0 comma space space space straight b space equals space 1
       therefore       straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space straight e to the power of 2 minus 0 end exponent space equals space straight e squared
                  straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight e to the power of 2 minus 3 straight h end exponent
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis 2 straight h right parenthesis space equals space straight e to the power of 2 minus 6 straight h end exponent
                .............................................
                        straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight e to the power of 2 minus 3 left parenthesis straight n minus 1 right parenthesis space straight h end exponent
    integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis space plus space straight f left parenthesis straight a plus straight h right parenthesis space plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                        equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight e squared plus straight e to the power of 2 minus 3 straight h end exponent plus straight e to the power of 2 minus 6 straight h end exponent plus.... plus straight e to the power of 2 minus left parenthesis straight n minus 1 right parenthesis straight h end exponent close square brackets
equals space Lt with straight h rightwards arrow 0 below space straight e squared straight h space open square brackets 1 plus straight e to the power of negative 3 straight h end exponent plus straight e to the power of negative 6 straight h end exponent plus.... plus straight e to the power of negative left parenthesis straight n minus 1 right parenthesis space straight h end exponent close square brackets
equals space Lt with straight h rightwards arrow 0 below space straight e squared straight h open square brackets fraction numerator 1 left curly bracket 1 minus left parenthesis straight e to the power of negative 3 straight h end exponent right parenthesis to the power of straight n over denominator 1 minus straight e to the power of negative 3 straight h end exponent end fraction close square brackets space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space space straight S subscript straight n space equals space fraction numerator straight a left parenthesis 1 minus straight r to the power of straight n right parenthesis over denominator 1 minus straight r end fraction close square brackets
     equals space Lt with straight h rightwards arrow 0 below straight e squared open square brackets fraction numerator 1 minus straight e to the power of negative 3 space straight n space straight h end exponent over denominator begin display style fraction numerator 1 minus straight e to the power of negative 3 straight h end exponent over denominator straight h end fraction end style end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below space straight e squared open square brackets fraction numerator 1 minus straight e to the power of negative 3 left parenthesis 1 right parenthesis end exponent over denominator begin display style fraction numerator straight e to the power of negative 3 straight h end exponent minus 1 over denominator negative 3 straight h end fraction end style left parenthesis 3 right parenthesis end fraction close square brackets space space space space left square bracket because space straight n space straight h space equals space 1 space minus space 0 space space equals space 1 right square bracket
    equals space Lt with straight h rightwards arrow 0 below space straight e squared space open square brackets fraction numerator 1 minus straight e to the power of negative 3 end exponent over denominator 1 cross times 3 end fraction close square brackets space space space                                          open square brackets because space space Lt with straight x rightwards arrow 0 below space straight e to the power of straight x minus 1 end exponent over straight x equals space 1 close square brackets
    equals space 1 third straight e squared left parenthesis 1 minus straight e to the power of negative 3 end exponent right parenthesis space equals space 1 third left parenthesis straight e squared minus straight e to the power of negative 1 end exponent right parenthesis
                  

    Question 28
    CBSEENMA12032370

    Evaluate integral subscript 0 superscript 3 straight e to the power of straight x space dx as the  limit of sums.

    Solution

    Comparing integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space with space integral subscript 0 superscript 3 straight e to the power of straight x dx comma space we space get
                               straight f left parenthesis straight x right parenthesis space equals space straight e to the power of straight x comma space space space straight a space equals space 0 comma space space space straight b space equals space 3
straight f left parenthesis straight a right parenthesis space equals space straight f left parenthesis 0 right parenthesis space equals space straight e to the power of 0 space equals space 1
straight f left parenthesis straight a plus straight h right parenthesis space equals space straight f left parenthesis straight h right parenthesis space equals space straight e to the power of straight h
straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight f left parenthesis space 2 space straight h right parenthesis space equals space straight e to the power of 2 straight h end exponent
                     .....................................................
                            straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis space equals space straight e to the power of left parenthesis straight n minus 1 right parenthesis space straight h end exponent
    Now            integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    rightwards double arrow             integral subscript 0 superscript 3 straight e to the power of straight x dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket 1 plus straight e to the power of straight h plus straight e to the power of 2 straight h end exponent plus.... plus straight e to the power of left parenthesis straight n minus 1 right parenthesis space straight h end exponent right square bracket
                                      equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator 1 left parenthesis straight e to the power of straight n space straight h end exponent minus 1 right parenthesis over denominator straight e to the power of straight h minus 1 end fraction close square brackets                          open square brackets because space space straight S subscript straight n space equals space fraction numerator straight a left parenthesis straight r to the power of straight n minus 1 right parenthesis over denominator straight r minus 1 end fraction close square brackets
                                      equals Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator straight e cubed minus 1 over denominator straight e to the power of straight h minus 1 end fraction close square brackets                      open square brackets because space nh space equals space straight b minus straight a space equals space 3 minus 0 space equals space 3 close square brackets
                                      equals left parenthesis straight e cubed minus 1 right parenthesis space Lt with straight h rightwards arrow 0 below space fraction numerator 1 over denominator begin display style fraction numerator straight e to the power of straight h minus 1 over denominator straight h end fraction end style end fraction space equals space left parenthesis straight e cubed minus 1 right parenthesis. space 1 over 1 space equals space straight e cubed minus 1

    Question 29
    CBSEENMA12032371

    Evaluate integral subscript 0 superscript 4 left parenthesis straight x plus straight e to the power of 2 straight x end exponent right parenthesis space dx as the limit of a sum.

    Solution

    Comparing integral subscript 0 superscript 4 left parenthesis straight x plus straight e to the power of 2 straight x end exponent right parenthesis dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis comma space we space get
                 straight f left parenthesis straight x right parenthesis space equals space straight x plus straight e to the power of 2 straight x end exponent comma space space straight a space equals space 0 comma space space straight b space equals space 4
    Now, integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    therefore     integral subscript 0 superscript 4 left parenthesis straight x plus straight e to the power of 2 straight x end exponent right parenthesis space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis 0 right parenthesis plus straight f left parenthesis straight h right parenthesis plus straight f left parenthesis 2 straight h right parenthesis plus... plus straight f left parenthesis stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
            equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket left parenthesis 0 plus straight e to the power of 0 right parenthesis space plus left parenthesis straight h plus straight e to the power of 2 straight h end exponent right parenthesis space plus space left parenthesis 2 straight h plus straight e to the power of 4 straight h end exponent right parenthesis plus... plus left curly bracket left parenthesis straight n minus 1 right parenthesis space straight h space plus straight e to the power of 2 left parenthesis straight n minus 1 right parenthesis straight h end exponent right curly bracket right square bracket
             equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight h left parenthesis 1 plus 2 plus 3 plus... plus stack straight n minus 1 with bar on top right parenthesis plus left parenthesis 1 plus straight e to the power of 2 straight h end exponent plus straight e to the power of 4 straight h end exponent plus... plus straight e to the power of 2 left parenthesis straight n minus 1 right parenthesis space straight h end exponent right parenthesis right square bracket
             equals space Lt with straight h rightwards arrow 0 below space straight h space open square brackets straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n right parenthesis over denominator 2 end fraction plus fraction numerator 1 left parenthesis straight e to the power of 2 nh end exponent minus 1 right parenthesis over denominator straight e to the power of 2 straight h end exponent minus 1 end fraction close square brackets space space space space space space space space space space space space space open square brackets because straight S subscript straight n space equals space fraction numerator straight a left parenthesis straight r to the power of straight n minus 1 right parenthesis over denominator straight r minus 1 end fraction comma space straight r greater than 1 close square brackets
equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator left parenthesis straight n space straight h minus straight h right parenthesis space left parenthesis straight n space straight h right parenthesis over denominator 2 end fraction plus fraction numerator straight e to the power of 2 nh end exponent minus 1 over denominator 2 cross times begin display style fraction numerator straight e to the power of 2 straight h end exponent minus 1 over denominator 2 straight h end fraction end style end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below space open square brackets fraction numerator left parenthesis 4 minus straight h right parenthesis space left parenthesis 4 right parenthesis over denominator 2 end fraction plus fraction numerator straight e to the power of 8 minus 1 over denominator 2 cross times begin display style fraction numerator straight e to the power of 2 straight h end exponent minus 1 over denominator 2 straight h end fraction end style end fraction close square brackets
                                                                                               open square brackets because space straight n apostrophe straight h space equals space straight b minus straight a space equals space 4 minus 0 space equals space 4 close square brackets
               = fraction numerator left parenthesis 4 minus 0 right parenthesis space left parenthesis 4 right parenthesis over denominator 2 end fraction plus fraction numerator straight e to the power of 8 minus 1 over denominator 2 cross times loge end fraction space equals space 8 plus fraction numerator straight e to the power of 8 minus 1 over denominator 2 end fraction space equals space fraction numerator straight e to the power of 8 plus 15 over denominator 2 end fraction

    Question 30
    CBSEENMA12032372

    Evaluate integral subscript straight a superscript straight b space sinx space dx as the limit of a sum.

    Solution

    Comparing integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space with space integral subscript straight a superscript straight b sinx space dx space comma space we space get comma space space straight f left parenthesis straight x right parenthesis space equals space sin space straight x space
    Now, integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    therefore     integral subscript straight a superscript straight b sinx space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket sin space straight a space plus sin space left parenthesis straight a plus straight h right parenthesis plus sin left parenthesis straight a plus 2 straight h right parenthesis plus... sin left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator sin space open parentheses straight a plus begin display style fraction numerator nh minus straight h over denominator 2 end fraction end style close parentheses space sin begin display style nh over 2 end style over denominator sin begin display style straight h over 2 end style end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below space open parentheses fraction numerator begin display style straight h over 2 end style over denominator sin space begin display style straight h over 2 end style end fraction close parentheses space left square bracket 2 space sin space open parentheses straight a plus fraction numerator nh minus straight h over denominator 2 end fraction close parentheses. sin straight h over 2 right square bracket
    equals Lt with straight h rightwards arrow 0 below open parentheses fraction numerator begin display style straight h over 2 end style over denominator sin begin display style straight h over 2 end style end fraction close parentheses space open square brackets 2 space sin space open parentheses straight a plus fraction numerator straight b minus straight a minus straight h over denominator 2 end fraction close parentheses space sin space fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets          open square brackets because space straight n space straight h space equals space straight b minus straight a close square brackets
    equals space left parenthesis 1 right parenthesis space open square brackets 2 space sin space open parentheses straight a plus fraction numerator straight b minus straight a minus 0 over denominator 2 end fraction close parentheses space sin space fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets space equals 2 space sin fraction numerator straight b plus straight a over denominator 2 end fraction sin fraction numerator straight b minus straight a over denominator 2 end fraction equals cosa minus cosb

    Question 31
    CBSEENMA12032373

    Evaluate integral subscript straight a superscript straight b cosx space dx as the limit of a sum.

    Solution

    Comparing integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space with space integral subscript straight a superscript straight b cosx space dx comma we get,
                     straight f left parenthesis straight x right parenthesis space equals space cos space straight x
    Now,            integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h space left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top right parenthesis right square bracket
     therefore            integral subscript straight a superscript straight b cosx space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket cos space straight a plus space cos space left parenthesis straight a plus straight h right parenthesis plus space cos left parenthesis straight a plus 2 straight h right parenthesis plus... plus cos left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                                           equals space Lt with straight h rightwards arrow 0 below space straight h open square brackets fraction numerator cos open parentheses straight a plus begin display style fraction numerator nh minus straight h over denominator 2 end fraction end style close parentheses space sin begin display style hn over 2 end style over denominator sin begin display style straight h over 2 end style end fraction close square brackets
                                         equals space Lt with straight h rightwards arrow 0 below space open parentheses fraction numerator begin display style straight h over 2 end style over denominator sin begin display style straight h over 2 end style end fraction close parentheses space open square brackets 2 space cos space open parentheses straight a plus fraction numerator straight b minus ah over denominator 2 end fraction close parentheses space sin fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets
equals space left parenthesis 1 right parenthesis space open square brackets 2 space cos open parentheses straight a plus fraction numerator straight b minus straight a minus 0 over denominator 2 end fraction close parentheses sin fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets
equals space 2 space cos fraction numerator straight b plus straight a over denominator 2 end fraction sin fraction numerator straight b minus straight a over denominator 2 end fraction
equals space sinb space minus space sina

    Question 32
    CBSEENMA12032374

    Evaluate integral subscript straight a superscript straight b space sin squared straight x space dx as the limit of a sum.

    Solution

    Comparing integral subscript straight a superscript straight b space sin squared straight x space dx space space with space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx comma space we space get comma
                           straight f left parenthesis straight x right parenthesis space equals space sin squared straight x equals fraction numerator 1 minus cos space 2 straight x over denominator 2 end fraction space equals space 1 half left parenthesis 1 minus cos space 2 straight x right parenthesis
    Now,        integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space Lt with straight h rightwards arrow 0 below space straight h left square bracket straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis plus.... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
    therefore           integral subscript straight a superscript straight b sin squared straight x space dx space equals space Lt with straight h rightwards arrow 0 below straight h over 2 left square bracket left parenthesis 1 minus cos space 2 straight a plus left curly bracket 1 minus cos space 2 space left parenthesis straight a plus straight h right parenthesis right curly bracket
                                                   plus left curly bracket 1 minus cos 2 left parenthesis straight a plus 2 straight h right parenthesis right curly bracket plus.... plus right curly bracket space left curly bracket 1 minus cos space 2 left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right curly bracket right square bracket
    equals space Lt with straight h rightwards arrow 0 below straight h over 2 left square bracket straight n minus left curly bracket cos 2 straight a plus cos 2 left parenthesis straight a plus straight h right parenthesis plus cos 2 left parenthesis straight a plus 2 straight h right parenthesis plus... plus cos 2 left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right curly bracket right square bracket
    space space equals space Lt with straight h rightwards arrow 0 below space straight h over 2 open square brackets straight n minus fraction numerator cos space open curly brackets begin display style fraction numerator 2 straight a plus 2 straight a plus 2 left parenthesis straight n minus 1 right parenthesis straight h over denominator 2 end fraction end style close curly brackets sin open parentheses straight n begin display style fraction numerator 2 straight h over denominator 2 end fraction end style close parentheses over denominator sin open parentheses begin display style fraction numerator 2 straight h over denominator 2 end fraction end style close parentheses end fraction close square brackets
       equals space Lt with straight h rightwards arrow 0 below straight h over 2 open square brackets straight n minus fraction numerator cos left parenthesis 2 straight a plus left parenthesis straight n minus 1 right parenthesis space straight h right curly bracket space sin space straight n space straight h over denominator sin space straight h end fraction close square brackets space equals space Lt with straight h rightwards arrow 0 below 1 half open square brackets straight n space straight h minus fraction numerator cos left curly bracket 2 straight a plus left parenthesis nh minus straight h right parenthesis right curly bracket space sin space nh over denominator begin display style fraction numerator sin space straight h over denominator straight h end fraction end style end fraction close square brackets
equals space Lt with straight h rightwards arrow 0 below 1 half open square brackets straight b minus straight a minus fraction numerator cos left curly bracket 2 straight a plus left parenthesis straight b minus straight a minus straight h right parenthesis right curly bracket space sin left parenthesis straight b minus straight a right parenthesis over denominator begin display style fraction numerator sin space straight h over denominator straight h end fraction end style end fraction close square brackets
    space space equals space 1 half open square brackets straight b minus straight a minus fraction numerator cos left parenthesis 2 straight a plus straight b minus straight a minus 0 right parenthesis space sin left parenthesis straight b minus straight a right parenthesis over denominator 1 end fraction close square brackets space equals space 1 half left square bracket straight b minus straight a minus cos left parenthesis straight a plus straight b right parenthesis space sin left parenthesis straight b minus straight a right parenthesis right square bracket
       equals space 1 half open square brackets left parenthesis straight b minus straight a right parenthesis space minus space 1 half 2 space cos left parenthesis straight b plus straight a right parenthesis space sin left parenthesis straight b minus straight a right parenthesis right square bracket close square brackets
equals space 1 half open square brackets left parenthesis straight b minus straight a right parenthesis minus 1 half left parenthesis sin space 2 straight b space minus space sin space 2 straight a right parenthesis close square brackets
equals space 1 half open square brackets left parenthesis straight b minus straight a right parenthesis plus left parenthesis sin space straight a space cos space straight a space minus space sin space straight b space cos space straight b right parenthesis close square brackets
      
                                                         
     

    Question 33
    CBSEENMA12032375

    Evaluate the following definite integrals as limit of sums.
    integral subscript 2 superscript 3 straight x squared dx

    Solution

    Let             I = integral subscript 2 superscript 3 straight x squared dx
    Since    integral straight x squared dx space equals space straight x cubed over 3 space equals space straight F left parenthesis straight x right parenthesis comma space say.
    therefore    by second fundamental theorem,
                                         I = F(3) - F(2) = fraction numerator left parenthesis 3 right parenthesis cubed over denominator 3 end fraction minus fraction numerator left parenthesis 2 right parenthesis cubed over denominator 3 end fraction space equals space 9 minus 8 over 3 space equals space 19 over 3

    Question 34
    CBSEENMA12032376

    Evaluate the following definite integral
    integral subscript negative 1 end subscript superscript 1 left parenthesis straight x plus 1 right parenthesis space dx

    Solution

    Let I = integral subscript negative 1 end subscript superscript 1 left parenthesis straight x plus 1 right parenthesis space dx space equals space open square brackets fraction numerator left parenthesis straight x plus 1 right parenthesis squared over denominator 2 end fraction close square brackets subscript negative 1 end subscript superscript 1 space equals space 1 half space left square bracket left parenthesis straight x plus 1 right parenthesis squared right square bracket subscript negative 1 end subscript superscript 1
            equals space 1 half open square brackets left parenthesis 1 plus 1 right parenthesis squared minus left parenthesis negative 1 plus 1 right parenthesis squared close square brackets space equals space 1 half left parenthesis 4 minus 0 right parenthesis space equals space 2

    Question 35
    CBSEENMA12032377

    Evaluate the following definite integral
    integral subscript 2 superscript 3 1 over straight x dx


    Solution

    Let I = integral subscript 2 superscript 3 1 over straight x dx space equals space left square bracket log space straight x right square bracket subscript 2 superscript 3 space space equals space log space 3 space minus space log space 2 space equals space log space 3 over 2

    Question 36
    CBSEENMA12032378

    Evaluate the following definite integral
    integral subscript 0 superscript 8 straight x to the power of 5 over 3 end exponent dx



    Solution

    Let I = integral subscript 0 superscript 8 straight x to the power of 5 over 3 end exponent space dx space minus space open square brackets fraction numerator straight x to the power of begin display style 8 over 3 end style end exponent over denominator begin display style 8 over 3 end style end fraction close square brackets subscript 0 superscript 8 space equals space 3 over 8 open square brackets straight x to the power of 8 over 3 end exponent close square brackets subscript 0 superscript 8
                       equals space 3 over 8 open square brackets left parenthesis 8 right parenthesis to the power of 8 over 3 end exponent minus 0 close square brackets space equals space 3 over 8 left parenthesis 2 to the power of 8 minus 0 right parenthesis space equals space 3 over 8 cross times 256 space equals space 96

    Question 37
    CBSEENMA12032379

    Evaluate the following definite integral
    integral subscript 0 superscript 4 straight x to the power of 1 half end exponent dx





    Solution

    Let I =integral subscript 0 superscript 4 straight x to the power of 1 half end exponent dx space equals space open square brackets fraction numerator straight x to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction close square brackets subscript 0 superscript 4 space equals space 2 over 3 open square brackets straight x to the power of 3 over 2 end exponent close square brackets subscript 0 superscript 4 space equals space 2 over 3 open square brackets 4 to the power of 3 over 2 end exponent minus 0 close square brackets space equals space 2 over 3 cross times left parenthesis 2 cubed minus 0 right parenthesis space equals space 2 over 3 cross times 8 space equals space 16 over 3

    Question 38
    CBSEENMA12032380

    Evaluate the following definite integral
    integral subscript 0 superscript 4 open parentheses straight x plus straight x to the power of 3 over 2 end exponent close parentheses dx






    Solution

    Let I = integral subscript 0 superscript 4 space open parentheses straight x plus straight x to the power of 3 over 3 end exponent close parentheses dx space equals space open square brackets straight x squared over 2 plus fraction numerator straight x to the power of begin display style 5 over 2 end style end exponent over denominator begin display style 5 over 2 end style end fraction close square brackets subscript 0 superscript 4 space space space
           space equals space open square brackets straight x squared over 2 plus 2 over 5 straight x to the power of 5 over 2 end exponent close square brackets subscript 0 superscript 4 space equals space open parentheses 16 over 2 plus 2 over 5 cross times 4 to the power of 5 over 2 end exponent close parentheses space minus space left parenthesis 0 plus 0 right parenthesis
space equals space 8 plus 2 over 5 cross times 32 space equals space 8 plus 64 over 5 space equals space 104 over 5

    Question 39
    CBSEENMA12032381

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi space tanx space dx







    Solution

    Let I = integral subscript 0 superscript straight pi space tanx space dx space equals space left square bracket log open vertical bar cosx close vertical bar right square bracket subscript 0 superscript straight pi space equals space minus left square bracket log open vertical bar cos space straight pi close vertical bar space minus space left square bracket log open vertical bar cos space straight pi close vertical bar space minus log open vertical bar cos space 0 close vertical bar right square bracket
             equals space left square bracket negative log space 1 space space minus space log space 1 right square bracket space equals space 0

    Sponsor Area

    Question 40
    CBSEENMA12032382

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi over 2 end superscript space cos space 2 straight x space dx








    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript space cos space 2 straight x space dx space equals space open square brackets fraction numerator sin space 2 straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space 1 half left square bracket sin space 2 straight x right square bracket subscript 0 superscript straight pi over 2 end superscript space equals space 1 half left square bracket sin space space straight pi space minus space sin space 0 right square bracket space equals space 1 half left parenthesis 0 minus 0 right parenthesis space equals space 0

    Question 41
    CBSEENMA12032383

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi over 4 end superscript space sin space 2 straight x space dx









    Solution

    Let I = space integral subscript 0 superscript straight pi over 4 end superscript space sin space 2 straight x space dx space equals space open square brackets negative fraction numerator cos space 2 straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space minus 1 half open square brackets cos space 2 straight x close square brackets subscript 0 superscript straight pi over 4 end superscript
            equals negative 1 half left square bracket cos space straight pi over 2 minus cos space 0 right square bracket space equals space minus 1 half left parenthesis 0 minus 1 right parenthesis space equals space 1 half

    Question 42
    CBSEENMA12032384

    Evaluate the following definite integral
    integral subscript straight pi over 6 end subscript superscript straight pi over 4 end superscript space cosec space straight x space dx

    Solution

    Let I = integral subscript straight pi over 6 end subscript superscript straight pi over 4 end superscript space cos e c space x space d x space equals subscript blank superscript blank
open square brackets table row log cell open vertical bar cosecx minus cotx close vertical bar end cell end table close square brackets subscript straight pi over 6 end subscript superscript straight pi over 4 end superscript
             equals space log space open vertical bar cose space straight pi over 4 minus cot straight pi over 4 close vertical bar space minus space log space open vertical bar cosec straight pi over 6 minus cot straight pi over 6 close vertical bar
equals space log space open vertical bar square root of 2 minus 1 close vertical bar space minus space log space open vertical bar 2 minus square root of 3 close vertical bar
equals space log space left parenthesis square root of 2 minus 1 right parenthesis space minus space log space left parenthesis 2 minus square root of 3 right parenthesis space equals space log open parentheses fraction numerator square root of 2 minus 1 over denominator 2 minus square root of 3 end fraction close parentheses

    Question 43
    CBSEENMA12032385

    Evaluate the following definite integral
    integral subscript 4 superscript 5 straight e to the power of straight x dx

    Solution

    Let I = integral subscript 4 superscript 5 straight e to the power of straight x space dx space equals space open square brackets straight e to the power of straight x close square brackets subscript 4 superscript 5 space equals space straight e to the power of 5 space minus space straight e to the power of 4 space equals space straight e to the power of 4 left parenthesis straight e minus 1 right parenthesis

    Question 44
    CBSEENMA12032386

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi over 4 end superscript space left parenthesis 2 sec squared straight x plus straight x cubed plus 2 right parenthesis dx


    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space left parenthesis 2 sec squared straight x plus straight x cubed plus 2 right parenthesis space dx space equals space open square brackets 2 space tan space straight x plus straight x to the power of 4 over 4 plus 2 straight x close square brackets subscript 0 superscript straight pi over 4 end superscript
            = open square brackets 2 space tan straight pi over 4 plus open parentheses begin display style straight pi over 4 end style close parentheses to the power of 4 over 4 plus 2 open parentheses straight pi over 4 close parentheses close square brackets space minus space left square bracket 2 space tan space 0 space plus space 0 space plus 0 right square bracket
           equals space 2 cross times 1 plus straight pi to the power of 4 over 1024 plus straight pi over 2 minus left parenthesis 0 plus 0 plus 0 right parenthesis space equals space 2 plus straight pi to the power of 4 over 1024 plus straight pi over 2

    Question 45
    CBSEENMA12032387

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi over 4 end superscript left parenthesis 2 sec squared straight x plus straight x cubed plus 2 right parenthesis space dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript left parenthesis 2 sec squared straight x plus straight x cubed plus 2 right parenthesis space dx space equals space open square brackets 2 space tan space straight x space plus straight x to the power of 4 over 4 plus 2 straight x close square brackets subscript 0 superscript straight pi over 4 end superscript
           equals space open square brackets 2 space tan space straight pi over 4 plus open parentheses begin display style straight pi over 4 end style close parentheses to the power of 4 over 4 plus 2 open parentheses straight pi over 4 close parentheses close square brackets space minus left square bracket 2 space tan space 0 space plus space 0 space plus space 0 right square bracket

equals space 2 cross times 1 plus straight pi to the power of 4 over 1024 plus straight pi over 2 minus left parenthesis 0 plus 0 plus 0 right parenthesis space equals space 2 plus straight pi to the power of 4 over 1024 plus straight pi over 2

    Question 46
    CBSEENMA12032388

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi open parentheses sin squared straight x over 2 minus cos squared straight x over 2 close parentheses space dx

    Solution

    Let I = integral subscript 0 superscript straight pi open parentheses sin squared straight x over 2 minus cos squared straight x over 2 close parentheses dx
           equals negative integral subscript 0 superscript straight pi open parentheses cos squared straight x over 2 minus sin squared straight x over 2 close parentheses dx space equals space minus integral subscript 0 superscript straight pi cosx space dx space equals space minus open square brackets sin space straight x close square brackets subscript 0 superscript straight pi
equals negative left parenthesis sin space straight pi space minus space sin space 0 right parenthesis space equals space minus left parenthesis 0 minus 0 right parenthesis space equals space 0

    Question 47
    CBSEENMA12032389

    Evaluate the following definite integral
    integral subscript 1 superscript 2 left parenthesis 4 straight x cubed minus 5 straight x squared plus 6 straight x plus 9 right parenthesis space dx.


    Solution

    Let I = integral subscript 1 superscript 2 left parenthesis 4 straight x cubed minus 5 straight x squared plus 6 straight x plus 9 right parenthesis space dx
            equals space open square brackets fraction numerator 4 straight x to the power of 4 over denominator 4 end fraction minus fraction numerator 5 straight x cubed over denominator 3 end fraction plus fraction numerator 6 straight x squared over denominator 2 end fraction plus 9 straight x close square brackets subscript 1 superscript 2 space equals space open square brackets straight x to the power of 4 minus 5 over 3 straight x cubed plus 3 straight x squared plus 9 straight x close square brackets subscript 1 superscript 2
equals space open parentheses 16 minus 40 over 3 plus 12 plus 18 close parentheses space minus space open parentheses 1 minus 5 over 3 plus 3 plus 9 close parentheses space equals space 32 2 over 3 minus 11 1 third space equals space 21 1 third

    Question 48
    CBSEENMA12032390

    Evaluate integral subscript 0 superscript 1 fraction numerator dx over denominator square root of 1 plus straight x end root minus square root of straight x end fraction.

    Solution

    Let
     straight I space equals space integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 plus straight x end root minus square root of straight x end fraction dx space equals space integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 plus straight x end root minus square root of straight x end fraction cross times fraction numerator square root of 1 plus straight x end root plus square root of straight x over denominator square root of 1 plus straight x end root plus square root of straight x end fraction dx
space space space
       space equals space integral subscript 0 superscript 1 fraction numerator square root of 1 plus straight x end root plus square root of straight x over denominator left parenthesis 1 plus straight x right parenthesis minus straight x end fraction dx space equals space integral subscript 0 superscript 1 fraction numerator square root of 1 plus straight x end root plus square root of straight x over denominator 1 end fraction dx
        equals integral subscript 0 superscript 1 space open square brackets left parenthesis plus straight x right parenthesis to the power of 1 half end exponent plus straight x to the power of 1 half end exponent close square brackets space dx space space equals space open square brackets fraction numerator left parenthesis 1 plus straight x right parenthesis to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction plus fraction numerator straight x to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction close square brackets subscript 0 superscript 1
        equals space 2 over 3 open square brackets left parenthesis 1 plus straight x right parenthesis to the power of 3 over 2 end exponent plus straight x to the power of 3 over 2 end exponent close square brackets subscript 0 superscript 1 space equals space 2 over 3 open square brackets open parentheses 2 to the power of 3 over 2 end exponent plus 1 to the power of 3 over 2 end exponent close parentheses minus left parenthesis 1 plus 0 right parenthesis close square brackets
equals space 2 over 3 left square bracket 2 square root of 2 plus 1 minus 1 right square bracket space equals space 2 over 3 cross times 2 square root of 2 space equals space fraction numerator 4 square root of 2 over denominator 3 end fraction
         
       

    Question 49
    CBSEENMA12032391

    Evaluate integral subscript 0 superscript 1 space straight x space straight e to the power of straight x squared space dx

    Solution

    Let I = integral subscript 0 superscript 1 space straight x space straight e to the power of straight x squared end exponent space dx
    Let straight I subscript 1 space equals space integral space straight x space straight e to the power of straight x squared end exponent space dx
    Put straight x squared space equals space straight y comma space space    therefore space space space 2 space straight x space dx space equals space dy        rightwards double arrow   straight x space dx space equals space 1 half dx
    therefore            straight I subscript 1 space equals space 1 half integral straight e to the power of straight y dy space equals space 1 half straight e to the power of straight y space equals space 1 half straight e to the power of straight x squared end exponent space equals space straight F left parenthesis straight x right parenthesis comma space say
    therefore by second fundamental theorem,
                           I = F(1) - F(0) = 1 half straight e to the power of 1 minus 1 half straight e to the power of 0 space equals space 1 half straight e minus 1 half space equals space 1 half left parenthesis straight e minus 1 right parenthesis

    Question 50
    CBSEENMA12032392

    Evaluate the following integral:
    integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 minus straight x squared end root end fraction dx

    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 minus straight x squared end root end fraction dx space equals space left square bracket sin to the power of negative 1 end exponent straight x right square bracket subscript 0 superscript 1 space equals space sin to the power of negative 1 end exponent 1 space minus space sin to the power of negative 1 end exponent 0 space equals space straight pi over 2 minus 0 space equals space straight pi over 2

    Question 51
    CBSEENMA12032393

    Explain the following integral:
    space integral subscript 0 superscript 1 fraction numerator 1 over denominator 1 plus straight x squared end fraction dx

    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator dx over denominator 1 plus straight x squared end fraction space equals space left square bracket tan to the power of negative 1 end exponent straight x right square bracket subscript 0 superscript 1 space equals space tan to the power of negative 1 end exponent 1 minus tan to the power of negative 1 end exponent 0 space equals space straight pi over 4 minus 0 space equals space straight pi over 4

    Question 52
    CBSEENMA12032394

    Explain the following integral:
    integral subscript 2 superscript 3 fraction numerator 1 over denominator straight x squared minus 1 end fraction dx

    Solution

    Let I = integral subscript 2 superscript 3 fraction numerator dx over denominator straight x squared minus 1 end fraction space equals space 1 half open square brackets log space open parentheses fraction numerator straight x minus 1 over denominator straight x plus 1 end fraction close parentheses close square brackets subscript 2 superscript 3
           equals space 1 half open square brackets log space open parentheses fraction numerator 3 minus 1 over denominator 3 plus 1 end fraction close parentheses minus log open parentheses fraction numerator 2 minus 1 over denominator 2 plus 1 end fraction close parentheses close square brackets space equals space 1 half open parentheses log 1 half minus log 1 third close parentheses
equals space 1 half log open parentheses 1 half cross times 3 over 1 close parentheses space equals space 1 half log 3 over 2

    Question 53
    CBSEENMA12032395

    Explain the following integral:
    integral subscript 2 superscript 3 fraction numerator straight x over denominator straight x squared plus 1 end fraction dx

    Solution

    Let I = integral subscript 2 superscript 3 fraction numerator straight x over denominator straight x squared plus 1 end fraction dx space equals space 1 half integral subscript 2 superscript 3 fraction numerator 2 straight x over denominator straight x squared plus 1 end fraction dx space equals space 1 half left square bracket log left parenthesis straight x squared plus 1 right parenthesis right square bracket subscript 2 superscript 3 space space space
            equals space 1 half left parenthesis log space 10 space minus space log space 5 right parenthesis space equals space 1 half log open parentheses 10 over 5 close parentheses space equals space 1 half log 2

    Question 54
    CBSEENMA12032396

    Evaluate the following integral:
    integral subscript 1 superscript 2 fraction numerator dx over denominator left parenthesis straight x plus 1 right parenthesis space left parenthesis straight x plus 2 right parenthesis end fraction

    Solution

    Let I = integral subscript 1 superscript 2 fraction numerator 1 over denominator left parenthesis straight x plus 1 right parenthesis space left parenthesis straight x plus 2 right parenthesis end fraction dx space equals space integral subscript 1 superscript 2 open square brackets fraction numerator 1 over denominator left parenthesis straight x plus 1 right parenthesis left parenthesis negative 1 plus 2 right parenthesis end fraction plus fraction numerator 1 over denominator left parenthesis negative 2 plus 1 right parenthesis space left parenthesis straight x plus 2 end fraction close square brackets dx
             equals space integral subscript 1 superscript 2 open parentheses fraction numerator 1 over denominator straight x plus 1 end fraction minus fraction numerator 1 over denominator straight x plus 2 end fraction close parentheses dx space equals space open square brackets log left parenthesis straight x plus 1 right parenthesis minus log left parenthesis straight x plus 2 right parenthesis close square brackets subscript 1 superscript 2
equals space open square brackets log open parentheses fraction numerator straight x plus 1 over denominator straight x plus 2 end fraction close parentheses close square brackets subscript 1 superscript 2 space equals space log 3 over 4 minus log 2 over 3 equals space log open parentheses fraction numerator begin display style 3 over 4 end style over denominator begin display style 2 over 3 end style end fraction close parentheses space equals space log open parentheses 9 over 8 close parentheses

    Question 55
    CBSEENMA12032397

    Evaluate the following integral:
    integral subscript 1 superscript 2 fraction numerator 5 straight x squared over denominator straight x squared plus 4 straight x plus 3 end fraction dx

    Solution

    Let I = integral subscript 1 superscript 2 fraction numerator 5 straight x squared over denominator straight x squared plus 4 straight x plus 3 end fraction dx space equals space 5 integral subscript 1 superscript 2 fraction numerator straight x squared over denominator left parenthesis straight x plus 1 right parenthesis space left parenthesis straight x plus 3 right parenthesis end fraction dx
           equals space 5 integral subscript 1 superscript 2 open square brackets 1 plus fraction numerator left parenthesis negative 1 right parenthesis squared over denominator left parenthesis straight x plus 1 right parenthesis space left parenthesis negative 1 plus 3 right parenthesis end fraction plus fraction numerator left parenthesis negative 3 right parenthesis squared over denominator left parenthesis negative 3 plus 1 right parenthesis space left parenthesis straight x plus 3 right parenthesis end fraction close square brackets dx
equals space 5 integral subscript 1 superscript 2 open square brackets 1 plus fraction numerator 1 over denominator 2 left parenthesis straight x plus 1 right parenthesis end fraction minus fraction numerator 9 over denominator 2 left parenthesis straight x plus 3 right parenthesis end fraction close square brackets dx
equals space 5 open square brackets straight x plus 1 half log left parenthesis straight x plus 1 right parenthesis minus 9 over 2 log left parenthesis straight x plus 3 right parenthesis close square brackets subscript 1 superscript 2
          equals space 5 space open square brackets straight x plus 1 half log left parenthesis straight x plus 1 right parenthesis minus 9 over 2 log left parenthesis straight x plus 3 right parenthesis close square brackets subscript 1 superscript 2
equals space 5 open square brackets open parentheses 2 plus 1 half log 3 minus 9 over 2 log 5 close parentheses space minus space open parentheses 1 plus 1 half log 2 minus 9 over 2 log 4 close parentheses close square brackets
equals space 5 open square brackets 1 plus 1 half log 3 minus 9 over 2 log 5 minus 1 half log 2 plus 9 over 2 log 4 close square brackets
equals space 5 open square brackets 1 plus 1 half left parenthesis log 3 minus log 2 right parenthesis minus 9 over 2 left parenthesis log space 5 space minus log space 4 right parenthesis close square brackets
equals space 5 open square brackets 1 plus 1 half log open parentheses 3 over 2 close parentheses minus 9 over 2 log open parentheses 5 over 4 close parentheses close square brackets

    Question 56
    CBSEENMA12032398

    Evaluate the following integral
    space integral subscript 2 superscript 3 fraction numerator 1 over denominator straight x squared minus 1 end fraction dx



    Solution

    Let I = integral subscript 2 superscript 3 fraction numerator dx over denominator straight x squared minus 1 end fraction space equals space 1 half open square brackets log space open parentheses fraction numerator straight x minus 1 over denominator straight x plus 1 end fraction close parentheses close square brackets subscript 2 superscript 3
            equals space 1 half open square brackets log space open parentheses fraction numerator 3 minus 1 over denominator 3 plus 1 end fraction close parentheses space minus space log open parentheses fraction numerator 2 minus 1 over denominator 2 plus 1 end fraction close parentheses close square brackets space equals space 1 half open parentheses log space 1 half minus log 1 third close parentheses
equals space 1 half log open parentheses 1 half cross times 3 over 1 close parentheses space equals space 1 half log 3 over 2

    Question 57
    CBSEENMA12032399

    Evaluate the following integral:
    space space integral subscript 0 superscript 4 fraction numerator dx over denominator square root of straight x squared plus 2 straight x plus 3 end root end fraction

    Solution

    Let I = space integral subscript 0 superscript 4 fraction numerator dx over denominator square root of straight x squared plus 2 straight x plus 3 end root end fraction space equals space integral subscript 0 superscript 4 fraction numerator 1 over denominator square root of left parenthesis straight x squared plus 2 straight x plus 1 right parenthesis plus 2 end root end fraction dx
           = integral subscript 0 superscript 4 fraction numerator 1 over denominator square root of left parenthesis straight x plus 1 right parenthesis squared plus left parenthesis square root of 2 right parenthesis squared end root end fraction dx space equals space open square brackets log space open vertical bar left parenthesis straight x plus 1 right parenthesis plus square root of straight x squared plus 2 straight x plus 3 end root close vertical bar close square brackets subscript 0 superscript 4
           equals space log left parenthesis 5 plus square root of 27 right parenthesis space minus space log left parenthesis 1 plus square root of 3 right parenthesis space equals space log open parentheses fraction numerator 5 plus 3 square root of 3 over denominator 1 plus square root of 3 end fraction close parentheses

    Question 58
    CBSEENMA12032400

    Evaluate the following integral:
    integral subscript 4 superscript 9 fraction numerator square root of straight x over denominator open parentheses 30 minus straight x to the power of begin display style 3 over 2 end style end exponent close parentheses squared end fraction dx

    Solution

    Let I = integral subscript 4 superscript 9 fraction numerator square root of straight x over denominator open parentheses 30 minus straight x to the power of begin display style 3 over 2 end style end exponent close parentheses squared end fraction dx
    Let straight I subscript 1 space equals space integral fraction numerator square root of straight x over denominator open parentheses 30 minus straight x to the power of begin display style 3 over 2 end style end exponent close parentheses squared end fraction dx
    Put   30 minus straight x to the power of 3 over 2 end exponent space equals space straight t comma space space space therefore space space minus 3 over 2 straight x to the power of 1 half end exponent ax space equals space dt space space space space space space space rightwards double arrow space space space space square root of straight x space dx space space equals negative 2 over 3 dt
    therefore                straight I subscript 1 space equals space minus 2 over 3 integral 1 over straight t squared dt space equals negative 2 over 3 integral straight t to the power of negative 2 end exponent dt space equals space minus 2 over 3 fraction numerator straight t to the power of negative 1 end exponent over denominator negative 1 end fraction space equals space fraction numerator 2 over denominator 3 straight t end fraction
    therefore          integral fraction numerator square root of straight x over denominator open parentheses 30 minus straight x to the power of begin display style 3 over 2 end style end exponent close parentheses squared end fraction dx space equals space fraction numerator 2 over denominator 3 open parentheses 30 minus straight x to the power of begin display style 3 over 2 end style end exponent close parentheses end fraction space equals space straight F left parenthesis straight x right parenthesis comma space say.
    by the second fundamental theorem,
    I = F(9) - F(4) = 2 over 3 open square brackets fraction numerator 1 over denominator 30 minus 9 to the power of begin display style 3 over 2 end style end exponent end fraction close square brackets minus 1 third open square brackets fraction numerator 1 over denominator 30 minus 4 to the power of begin display style 3 over 2 end style end exponent end fraction close square brackets
           equals space 2 over 3 open square brackets fraction numerator 1 over denominator 30 minus 27 end fraction close square brackets minus 2 over 3 open square brackets fraction numerator 1 over denominator 30 minus 8 end fraction close square brackets space equals 2 over 3 cross times 1 third minus 2 over 3 cross times 1 over 22
equals space 2 over 3 open parentheses 1 third minus 1 over 22 close parentheses space equals space 2 over 3 cross times fraction numerator 22 minus 3 over denominator 66 end fraction space equals space 2 over 3 cross times 19 over 66 space equals space 19 over 99

    Question 59
    CBSEENMA12032401

    Evaluate the following definite integral
    integral subscript 0 superscript 2 fraction numerator 6 straight x plus 3 over denominator straight x squared plus 4 end fraction dx.

    Solution

    Let I = integral subscript 0 superscript 2 fraction numerator 6 straight x plus 3 over denominator straight x squared plus 4 end fraction dx space equals space 6 integral subscript 0 superscript 2 fraction numerator straight x over denominator straight x squared plus 4 end fraction dx plus 3 integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus 4 end fraction dx
           equals 3 integral subscript 0 superscript 2 fraction numerator 2 straight x over denominator straight x squared plus 4 end fraction dx plus 3 integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus left parenthesis 2 right parenthesis squared end fraction dx space equals space 3 left square bracket log left parenthesis straight x squared plus 4 right parenthesis right square bracket subscript 0 superscript 2 plus 3.1 half open square brackets tan to the power of negative 1 end exponent open parentheses straight x over 2 close parentheses close square brackets subscript 0 superscript 2
equals 3 left square bracket log space 8 space minus space log space 4 right square bracket space plus 3 over 2 left square bracket tan to the power of negative 1 end exponent 1 space minus space tan to the power of negative 1 end exponent 0 right square bracket space equals space 3 space log open parentheses 8 over 4 close parentheses plus 3 over 2 open parentheses straight pi over 4 minus 0 close parentheses
equals space 3 space log space 2 space plus space fraction numerator 3 straight pi over denominator 8 end fraction

    Question 60
    CBSEENMA12032402

    Evaluate the following definite integral
    integral subscript 0 superscript 1 fraction numerator 2 straight x over denominator 5 straight x squared plus 1 end fraction dx

    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator 2 straight x over denominator 5 straight x squared plus 1 end fraction dx space equals space 1 fifth integral fraction numerator 10 straight x over denominator 5 straight x squared plus 1 end fraction dx
space space
           equals space 1 fifth left square bracket log left parenthesis 5 straight x squared plus 1 right parenthesis right square bracket subscript 0 superscript 1 space equals space 1 fifth left square bracket log space 6 space minus log space 1 right square bracket space equals space 1 fifth log 6

    Question 61
    CBSEENMA12032403

    Evaluate the following definite integral:
    integral subscript 0 superscript 2 fraction numerator 5 straight x plus 1 over denominator straight x squared plus 4 end fraction dx


    Solution

    Let I = integral subscript 0 superscript 2 fraction numerator 5 straight x plus 1 over denominator straight x squared plus 4 end fraction dx space equals space integral subscript 0 superscript 2 fraction numerator 5 straight x over denominator straight x squared plus 4 end fraction dx plus integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus 4 end fraction dx
            equals space 5 over 2 integral subscript 0 superscript 2 fraction numerator 2 straight x over denominator straight x squared plus 4 end fraction dx plus integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus left parenthesis 2 right parenthesis squared end fraction dx
             equals space 5 over 2 open square brackets log left parenthesis straight x squared plus 4 right parenthesis close square brackets subscript 0 superscript 2 space plus space 1 half open square brackets tan to the power of negative 1 end exponent straight x over 2 close square brackets subscript 0 superscript 2
                                        open square brackets because space integral fraction numerator straight f apostrophe left parenthesis straight x right parenthesis over denominator straight f left parenthesis straight x right parenthesis end fraction dx space equals space log open vertical bar straight f left parenthesis straight x right parenthesis close vertical bar space and space integral fraction numerator 1 over denominator straight x squared plus straight a squared end fraction dx space equals space 1 over straight a tan to the power of negative 1 end exponent straight x over straight a close square brackets
                     equals space 5 over 2 left square bracket log space 8 minus space log space 4 right square bracket plus 1 half left square bracket tan to the power of negative 1 end exponent 1 space minus space tan to the power of negative 1 end exponent 0 right square bracket space equals space 5 over 2 log open parentheses 8 over 4 close parentheses plus 1 half open square brackets straight pi over 4 minus 0 close square brackets
equals space 5 over 2 log space 2 space plus space straight pi over 8

    Question 62
    CBSEENMA12032404

    Evaluate the following definite integral:
    integral subscript 0 superscript 1 fraction numerator 2 straight x plus 3 over denominator 5 straight x squared plus 1 end fraction dx



    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator 2 straight x plus 3 over denominator 5 straight x squared plus 1 end fraction dx
            equals space 2 integral subscript 0 superscript 1 fraction numerator xdx over denominator 5 straight x squared plus 1 end fraction plus 3 integral subscript 0 superscript 1 fraction numerator 1 over denominator 5 straight x squared plus 1 end fraction dx space equals space 2 over 10 integral subscript 0 superscript 1 fraction numerator 10 xdx over denominator 5 straight x squared plus 1 end fraction plus 3 over 5 integral subscript 0 superscript 1 fraction numerator 1 over denominator straight x squared plus begin display style 1 fifth end style end fraction dx
             equals space 1 fifth integral subscript 0 superscript 1 fraction numerator 10 straight x over denominator 5 straight x squared plus 1 end fraction dx plus 3 over 5 integral subscript 0 superscript 1 fraction numerator 1 over denominator straight x squared plus open parentheses begin display style fraction numerator 1 over denominator square root of 5 end fraction end style close parentheses squared end fraction dx
             equals space 1 fifth open square brackets log left parenthesis 5 straight x squared plus 1 right parenthesis close square brackets subscript 0 superscript 1 plus 3 over 5. fraction numerator 1 over denominator begin display style fraction numerator 1 over denominator square root of 5 end fraction end style end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight x over denominator begin display style fraction numerator 1 over denominator square root of 5 end fraction end style end fraction close parentheses close square brackets subscript 0 superscript 1
             equals space 1 fifth left parenthesis log space 6 minus log 1 right parenthesis plus fraction numerator 3 over denominator square root of 5 end fraction left square bracket tan to the power of negative 1 end exponent square root of 5 minus tan to the power of negative 1 end exponent 0 right square bracket
equals space 1 fifth left parenthesis log space 6 space minus 0 right parenthesis plus fraction numerator 3 over denominator square root of 5 end fraction left square bracket tan to the power of negative 1 end exponent square root of 5 minus 0 right square bracket space equals space 1 fifth log space 6 space plus space fraction numerator 3 over denominator square root of 5 end fraction tan to the power of negative 1 end exponent square root of 5

    Question 63
    CBSEENMA12032405
    Question 64
    CBSEENMA12032406

    Evaluate the following definite integral:
    integral subscript 0 superscript straight pi over 2 end superscript space straight x squared space sinx space dx.
       




    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript space straight x squared space sinx space dx space equals space open square brackets straight x squared left parenthesis negative left parenthesis cosx right parenthesis close square brackets subscript 0 superscript straight pi over 2 end superscript space minus space integral subscript 0 superscript straight pi divided by 2 end superscript space 2 straight x space left parenthesis negative cos space straight x right parenthesis space dx
       equals space minus space open square brackets straight x squared space cosx close square brackets subscript 0 superscript straight pi divided by 2 end superscript space plus space 2 space integral subscript 0 superscript straight pi divided by 2 end superscript straight x space cosx space dx
        equals negative open square brackets straight x squared space cosx close square brackets subscript 0 superscript straight pi divided by 2 end superscript plus 2 open curly brackets open square brackets straight x space sinx close square brackets subscript 0 superscript straight pi over 2 end superscript space minus space integral subscript 0 superscript straight pi over 2 end superscript space 1. space sin space straight x space dx close curly brackets
        equals negative open square brackets straight x squared space cosx close square brackets subscript 0 superscript straight pi divided by 2 end superscript space plus space 2 open square brackets straight x space sinx close square brackets subscript 0 superscript straight pi divided by 2 end superscript space plus space 2 open square brackets cos space straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript
equals space minus open square brackets straight pi squared over 4 cos straight pi over 2 minus 0 close square brackets space plus space 2 open square brackets straight pi over 2 space sin straight pi over 2 minus 0 close square brackets space plus space 2 open square brackets cos space straight pi over 2 minus cos space 0 close square brackets
equals space minus left parenthesis 0 minus 0 right parenthesis plus 2 open parentheses straight pi over 2 minus 0 close parentheses plus 2 space left parenthesis 0 minus 1 right parenthesis space equals space 0 plus straight pi minus 2 space equals space straight pi minus 2.

    Question 65
    CBSEENMA12032407

    Evaluate the following definite integral:
    integral subscript 0 superscript straight pi over 4 end superscript space sin space 2 straight x space sin space 3 straight x space dx.

       




    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space sin space 2 straight x space sin space 3 straight x space dx space equals space 1 half integral subscript 0 superscript straight pi over 4 end superscript left parenthesis space 2 space sin space 3 straight x space sin space 2 straight x right parenthesis space dx
              equals space 1 half integral subscript 0 superscript straight pi over 4 end superscript left square bracket space cos space left parenthesis 3 straight x minus 2 straight x right parenthesis space minus space cos space left parenthesis 3 straight x plus 2 straight x right parenthesis right square bracket space dx space equals space 1 half integral subscript 0 superscript straight pi over 4 end superscript left parenthesis cosx space minus space cos space 5 straight x right parenthesis space dx
               equals space 1 half open square brackets sin space straight x minus space fraction numerator sin space 5 straight x over denominator 5 end fraction close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space 1 half open square brackets open parentheses sin space straight pi over 4 minus 1 fifth sin fraction numerator 5 straight pi over denominator 4 end fraction close parentheses minus open parentheses sin space 0 minus 1 fifth sin space 0 close parentheses close square brackets
               equals 1 half open square brackets open parentheses sin space straight pi over 4 plus 1 fifth sin straight pi over 4 close parentheses minus open parentheses sin space 0 space minus space 1 fifth sin space 0 close parentheses close square brackets
equals space 1 half open square brackets open parentheses fraction numerator 1 over denominator square root of 2 end fraction plus 1 fifth cross times fraction numerator 1 over denominator square root of 2 end fraction close parentheses minus left parenthesis 0 minus 0 right parenthesis close square brackets space equals space 1 half open square brackets 6 over 5 cross times fraction numerator 1 over denominator square root of 2 end fraction close square brackets space equals space fraction numerator 3 over denominator 5 square root of 2 end fraction

    Question 66
    CBSEENMA12032408

    Evaluate the following definite integral
    integral subscript 0 superscript straight pi over 4 end superscript space sin cubed space 2 straight t space cos space 2 straight t space dt

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space sin cubed space 2 straight t space cos space 2 straight t space dt
    Let straight I subscript 1 space equals space integral space sin cubed space 2 straight t space cos space 2 straight t space dt
    Put  sin 2t = y;   therefore space space 2 space cos space 2 dt space dt space equals space dy space space rightwards double arrow space space space space cos space 2 straight t space dt space equals space 1 half dy
    therefore     straight I subscript 1 space equals space 1 half integral straight y cubed dy space equals space 1 half cross times straight y to the power of 4 over 4 space equals space 1 over 8 sin to the power of 4 2 straight t space equals space straight F left parenthesis straight t right parenthesis comma space say.
    By second fundamental theorem,
    straight I space equals space straight F open parentheses straight pi over 4 close parentheses minus straight F left parenthesis 0 right parenthesis space equals space 1 over 8 sin to the power of 4 straight pi over 2 minus 1 over 8 sin to the power of 4 0 space equals space 1 over 8 left parenthesis 1 right parenthesis to the power of 4 minus 1 over 8 left parenthesis 0 right parenthesis to the power of 4 space equals space 1 over 8 minus 0 space equals space 1 over 8

    Question 67
    CBSEENMA12032409
    Question 68
    CBSEENMA12032410

    Prove the following:
    integral subscript 0 superscript straight pi over 2 end superscript space sin cubed straight x space dx space equals space 2 over 3

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript sin cubed straight x space dx
             equals 1 fourth integral subscript 0 superscript straight pi over 2 end superscript left parenthesis 3 space sinx minus space sin space 3 straight x right parenthesis space dx
              equals space 1 fourth open square brackets negative 3 space cosx plus 1 third cos space 3 straight x close square brackets subscript 0 superscript straight pi over 2 end superscript
              equals space 1 fourth open square brackets open parentheses negative 3 space cos straight pi over 2 plus 1 third cos fraction numerator 3 straight pi over denominator 2 end fraction close parentheses minus open parentheses negative 3 space cos 0 plus 1 third cos 0 close parentheses close square brackets
equals space 1 fourth open square brackets negative left parenthesis 3 right parenthesis space left parenthesis 0 right parenthesis plus open parentheses 1 half close parentheses left parenthesis 0 right parenthesis plus 3 minus 1 third close square brackets space equals space 1 fourth open parentheses 8 over 3 close parentheses space equals space 2 over 3

    Question 69
    CBSEENMA12032411

    Evaluate the following
    integral subscript 0 superscript straight pi over 4 end superscript space tan to the power of 4 straight x space dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space tan to the power of 4 straight x space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript space tan squared straight x. space space tan squared straight x space dx
            equals space integral subscript 0 superscript straight pi over 4 end superscript space tan squared straight x space left parenthesis sec squared straight x minus 1 right parenthesis space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript left parenthesis tan squared xsec squared straight x minus tan squared straight x right parenthesis space dx
             equals space integral subscript 0 superscript straight pi over 4 end superscript left parenthesis tan squared straight x space sec squared straight x minus sec squared straight x plus 1 right parenthesis space dx space equals space open square brackets fraction numerator tan cubed straight x over denominator 3 end fraction minus tanx plus straight x close square brackets subscript 0 superscript straight pi over 4 end superscript
               equals open parentheses 1 third tan cubed straight pi over 4 minus tan straight pi over 4 plus straight pi over 4 close parentheses space minus space open parentheses 1 third tan cubed 0 minus tan space 0 space plus 0 close parentheses
equals space open parentheses 1 third cross times 1 minus 1 plus straight pi over 4 close parentheses space minus space left parenthesis 0 plus 0 plus 0 right parenthesis space equals space 1 third minus 1 plus straight pi over 4 space equals space straight pi over 4 minus 2 over 3

    Question 70
    CBSEENMA12032413

    Evaluate the following:
    integral subscript 0 superscript straight pi over 4 end superscript space tan to the power of 4 space straight x space dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space tan to the power of 4 straight x space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript space tan squared straight x. space tan squared straight x space dx
             equals space integral subscript 0 superscript straight pi over 4 end superscript space tan squared straight x left parenthesis sec squared straight x minus 1 right parenthesis space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript left parenthesis tan squared straight x space sec squared straight x minus tan squared straight x right parenthesis space dx
            equals space integral subscript 0 superscript straight pi over 4 end superscript space left parenthesis tan squared straight x space sec squared straight x minus sec squared straight x plus 1 right parenthesis space dx space equals space open square brackets fraction numerator tan cubed straight x over denominator 3 end fraction minus tanx plus straight x close square brackets subscript 0 superscript straight pi over 4 end superscript
             equals space open parentheses 1 third tan cubed straight pi over 4 minus tan straight pi over 4 plus straight pi over 4 close parentheses space minus space open parentheses 1 third tan cubed 0 minus tan 0 plus 0 close parentheses
equals space open parentheses 1 third cross times 1 minus 1 plus straight pi over 4 close parentheses minus left parenthesis 0 plus 0 plus 0 right parenthesis space equals space 1 third minus 1 plus straight pi over 4 equals straight pi over 4 minus 2 over 3

    Question 71
    CBSEENMA12032414

    Evaluate the following:
    integral subscript 0 superscript straight pi over 4 end superscript square root of 1 minus sin space 2 straight x end root dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript square root of 1 minus sin space 2 straight x end root dx space equals space integral subscript 0 superscript straight pi over 4 end superscript square root of cos squared straight x plus sin squared straight x minus 2 sinx space cosx end root dx
            equals space integral subscript 0 superscript straight pi over 4 end superscript space square root of left parenthesis cosx minus sinx right parenthesis squared end root space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript left parenthesis cosx minus sinx right parenthesis space dx
              equals left square bracket sinx plus cosx right square bracket subscript 0 superscript straight pi over 4 end superscript space equals space open parentheses sin straight pi over 4 plus cos straight pi over 4 close parentheses minus left parenthesis sin 0 plus cos 0 right parenthesis
equals space open parentheses fraction numerator 1 over denominator square root of 2 end fraction plus fraction numerator 1 over denominator square root of 2 end fraction close parentheses space minus space left parenthesis 0 plus 1 right parenthesis space equals space fraction numerator 2 over denominator square root of 2 end fraction minus 1 space equals square root of 2 minus 1.

    Question 72
    CBSEENMA12032415

    Prove the following:
    integral subscript 0 superscript 1 open parentheses straight x space straight e to the power of straight x plus sin πx over 4 close parentheses dx space equals space 1 plus 4 over straight pi minus fraction numerator 2 square root of 2 over denominator straight pi end fraction

    Solution

    Let I = integral subscript 0 superscript 1 open parentheses xe to the power of straight x plus sin πx over 4 close parentheses space dx
           equals space integral subscript 0 superscript 1 straight x space straight e to the power of straight x space dx space plus space integral subscript 0 superscript 1 sin πx over 4 dx space equals space left square bracket straight x space straight e to the power of straight x right square bracket subscript 0 superscript 1 space minus space integral subscript 0 superscript 1 1. space straight e to the power of straight x dx plus open square brackets fraction numerator negative cos begin display style πx over 4 end style over denominator begin display style straight pi over 4 end style end fraction close square brackets subscript 0 superscript 1
           equals left square bracket straight x space straight e to the power of straight x right square bracket subscript 0 superscript 1 space minus space left square bracket straight e to the power of straight x right square bracket subscript 0 superscript 1 space minus space 4 over straight pi open square brackets cos fraction numerator straight pi space straight x over denominator 4 end fraction close square brackets subscript 0 superscript 1 space equals space left parenthesis straight e minus 0 right parenthesis minus left parenthesis straight e minus straight e to the power of 0 right parenthesis minus 4 over straight pi open square brackets cos straight pi over 4 minus cos space 0 close square brackets
equals space straight e minus straight e plus 1 minus 4 over straight pi open parentheses fraction numerator 1 over denominator square root of 2 end fraction minus 1 close parentheses space equals space 1 plus 4 over straight pi minus fraction numerator 2 square root of 2 over denominator straight pi end fraction

    Question 73
    CBSEENMA12032416

    Prove the following:
    integral subscript 0 superscript 1 straight x space straight e to the power of straight x space dx space equals space 1



    Solution

    Let I = integral subscript 0 superscript 1 xe to the power of straight x space dx space equals space left square bracket straight x space straight e to the power of straight x right square bracket subscript 0 superscript 1 space minus space integral subscript 0 superscript 1 1. space straight e to the power of straight x dx
          equals space left square bracket xe to the power of straight x right square bracket subscript 0 superscript 1 space minus space left square bracket straight e to the power of straight x right square bracket subscript 0 superscript 1 space equals space left parenthesis straight e minus 0 right parenthesis space minus space left parenthesis straight e minus straight e to the power of 0 right parenthesis space equals space straight e minus straight e plus 1 space equals space 1

    Question 74
    CBSEENMA12032417

    Evaluate
    integral subscript 0 superscript 1 open parentheses straight x space straight e to the power of straight x plus cos πx over 4 close parentheses dx

    Solution

    Let I = integral subscript 0 superscript 1 open parentheses straight x space straight e to the power of straight x plus cos πx over 4 close parentheses dx space equals integral subscript 0 superscript 1 xe to the power of straight x dx plus integral subscript 0 superscript 1 cos πx over 4 dx
           equals left square bracket space straight x space straight e to the power of straight x right square bracket subscript 0 superscript 1 space minus space integral subscript 0 superscript 1 1. space straight e to the power of straight x dx plus open square brackets fraction numerator sin space begin display style fraction numerator straight pi space straight x over denominator 4 end fraction end style over denominator begin display style straight pi over 4 end style end fraction close square brackets subscript 0 superscript 1 space equals space left square bracket straight x space straight e to the power of straight x right square bracket subscript 0 superscript 1 minus open square brackets straight e to the power of straight x close square brackets subscript 0 superscript 1 plus 4 over straight pi open square brackets sin space πx over 4 close square brackets subscript 0 superscript 1
           equals space left parenthesis straight e minus 0 right parenthesis space minus space left parenthesis straight e minus straight e to the power of 0 right parenthesis space plus space 4 over straight pi open parentheses sin space straight pi over 4 minus sin space 0 close parentheses
          equals straight e minus straight e plus 1 plus 4 over straight pi open parentheses fraction numerator 1 over denominator square root of 2 end fraction minus 0 close parentheses space equals space 1 plus fraction numerator 2 square root of 2 over denominator straight pi end fraction

    Question 75
    CBSEENMA12032419

    Evaluate
    integral subscript 0 superscript 1 open parentheses xe to the power of 2 straight x end exponent plus sin πx over 2 close parentheses dx

    Solution

    Let I = integral subscript 0 superscript 1 open parentheses xe to the power of 2 straight x end exponent plus sin πx over 2 close parentheses dx equals space integral subscript 0 superscript 1 straight x space straight e to the power of 2 straight x end exponent dx plus integral subscript 0 superscript 1 sin πx over 2 dx
            equals space open square brackets straight x straight e to the power of 2 straight x end exponent over 2 close square brackets subscript 0 superscript 1 minus integral subscript 0 superscript 1 1. space straight e to the power of 2 straight x end exponent over 2 dx plus open square brackets fraction numerator negative cos space begin display style πx over 2 end style over denominator begin display style straight pi over 2 end style end fraction close square brackets subscript 0 superscript 1
          equals space 1 half left square bracket straight x space straight e to the power of 2 straight x end exponent right square bracket subscript 0 superscript 1 space minus space 1 fourth left square bracket straight e to the power of 2 straight x end exponent right square bracket subscript 0 superscript 1 space minus space 2 over straight pi open square brackets cos πx over 2 close square brackets subscript 0 superscript 1
equals space 1 half left parenthesis straight e squared minus 0 right parenthesis space minus 1 fourth left parenthesis straight e squared minus straight e to the power of 0 right parenthesis space equals space 2 over straight pi open parentheses cos space straight pi over 2 minus cos space 0 close parentheses
equals space 1 half straight e squared minus 1 fourth left parenthesis straight e squared minus 1 right parenthesis space minus 2 over straight pi left parenthesis 0 minus 1 right parenthesis space equals space 1 half straight e squared minus 1 fourth straight e squared plus 1 fourth plus 2 over straight pi space equals 1 fourth straight e squared plus 1 fourth plus 2 over straight pi

    Question 76
    CBSEENMA12032422

    Evaluate:
    integral subscript straight pi over 2 end subscript superscript straight pi space straight e to the power of straight x open parentheses fraction numerator 1 minus sinx over denominator 1 minus cosx end fraction close parentheses dx



    Solution

    Let I = integral subscript straight pi over 2 end subscript superscript straight pi space straight e to the power of straight x open parentheses fraction numerator 1 minus sinx over denominator 1 minus cosx end fraction close parentheses dx space equals space integral subscript straight pi over 2 end subscript superscript straight pi straight e to the power of straight x space open square brackets fraction numerator 1 minus 2 sin begin display style straight x over 2 end style cos begin display style straight x over 2 end style over denominator 2 sin squared begin display style straight x over 2 end style end fraction close square brackets dx
          equals space integral subscript straight pi over 2 end subscript superscript straight pi space straight e to the power of straight x open square brackets fraction numerator 1 over denominator 2 sin squared begin display style straight x over 2 end style end fraction minus fraction numerator 2 sin begin display style straight x over 2 end style cos begin display style straight x over 2 end style over denominator 2 sin squared begin display style straight x over 2 end style end fraction close square brackets space dx space equals space integral subscript straight pi over 2 end subscript superscript straight pi straight e to the power of straight x open square brackets 1 half cosec squared straight x over 2 minus cot straight x over 2 close square brackets dx
         equals space integral subscript straight pi over 2 end subscript superscript straight pi over 2 end superscript straight e to the power of straight x space open square brackets negative cot straight x over 2 plus 1 half cosec squared straight x over 2 close square brackets dx
         equals space open square brackets straight e to the power of straight x space open parentheses negative cot straight x over 2 close parentheses close square brackets subscript straight pi over 2 end subscript superscript straight pi                            open square brackets because space space space integral space straight e to the power of straight x space left curly bracket straight f left parenthesis straight x right parenthesis plus straight f apostrophe left parenthesis straight x right parenthesis right curly bracket dx space equals space straight e to the power of straight x space straight f left parenthesis straight x right parenthesis close square brackets
         equals negative open square brackets straight e to the power of straight x open parentheses negative cot straight x over 2 close parentheses close square brackets subscript straight pi over 2 end subscript superscript straight pi space equals space minus open square brackets straight e to the power of straight pi cot straight pi over 2 minus straight e to the power of straight pi over 2 end exponent cot straight pi over 4 close square brackets
equals negative open square brackets straight e to the power of straight pi space cross times 0 minus straight e to the power of straight pi over 2 end exponent cross times 1 close square brackets space equals space straight e to the power of straight pi over 2 end exponent
         

    Question 77
    CBSEENMA12032423

    If integral subscript 0 superscript straight a 3 space straight x squared space dx space equals space 8.
    find the value of a.

    Solution
    integral subscript 0 superscript straight a space 3 straight x squared dx space equals space 8
    rightwards double arrow space space space space open square brackets fraction numerator 3 straight x cubed over denominator 3 end fraction close square brackets subscript 0 superscript straight a space equals space 8                    rightwards double arrow space space space space space straight a cubed space equals space 8 space space space space space space space rightwards double arrow space space space space straight a space space equals space 2
    Question 78
    CBSEENMA12032425

    If integral subscript straight a superscript straight b straight x cubed dx space equals space 0 space and space if space integral subscript straight a superscript straight b straight x squared dx space equals space 2 over 3. find both a and b.

    Solution
    integral subscript straight a superscript straight b space straight x cubed space dx space equals space 0 space space space rightwards double arrow space space open square brackets straight x to the power of 4 over 4 close square brackets subscript straight a superscript straight b space equals space 0
    rightwards double arrow space space space space 1 fourth left parenthesis straight b to the power of 4 minus straight a to the power of 4 right parenthesis space space equals space 0 space rightwards double arrow space straight b to the power of 4 minus straight a to the power of 4 space equals space 0
rightwards double arrow space space space space space left parenthesis straight b squared minus straight a squared right parenthesis space left parenthesis straight b squared plus straight a squared right parenthesis space equals space 0 space space rightwards double arrow space space straight b squared minus straight a squared space equals space 0 space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space space straight b squared plus straight a squared space not equal to 0 close square brackets
rightwards double arrow space space space space space left parenthesis straight b minus straight a right parenthesis space left parenthesis straight b plus straight a right parenthesis space equals space 0 space space rightwards double arrow space space space straight b plus straight a space equals space 0 space space space space space space space open square brackets because space straight b not equal to straight a space as space integral subscript straight a superscript straight b straight x squared dx not equal to 0 close square brackets
therefore space space space space straight b space equals space minus straight a space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space... left parenthesis 1 right parenthesis
       Also      integral subscript straight a superscript straight b straight x squared dx space equals space 2 over 3 space space space space space space space space rightwards double arrow space space space space space space space open square brackets straight x cubed over 3 close square brackets subscript straight a superscript straight b space equals space 2 over 3

    rightwards double arrow     1 third left parenthesis straight b cubed minus straight a cubed right parenthesis space equals space 2 over 3         rightwards double arrow       straight b cubed minus straight a cubed space equals space 2
     
    therefore      left parenthesis negative straight a right parenthesis cubed minus straight a cubed space equals space 2                                             open square brackets because space space of space left parenthesis 1 right parenthesis close square brackets
     
    therefore        negative space 2 space straight a cubed space equals space 2                   rightwards double arrow    straight a cubed equals negative 1      rightwards double arrow     a = -1
    therefore  we have a = -1,   b = 1
    Question 79
    CBSEENMA12032427

    If f (x) is of the form f (x) = a+b x+cx2, show that
    integral subscript 0 superscript 1 straight f left parenthesis straight x right parenthesis space dx space equals space 1 over 6 open curly brackets straight f left parenthesis 0 right parenthesis space plus space 4 space straight f space open parentheses 1 half close parentheses plus straight f left parenthesis 1 right parenthesis close curly brackets.

    Solution

    Here straight f left parenthesis straight x right parenthesis space equals space straight a plus straight b plus cx squared
    therefore space space straight f left parenthesis 0 right parenthesis space equals space straight a plus 0 plus 0 space equals space straight a comma space space space straight f open parentheses 1 half close parentheses space equals space straight a plus straight b over straight c plus straight c over 4 comma space space space straight f left parenthesis 1 right parenthesis space equals space straight a plus straight b plus straight c
    R.H.S. = 1 over 6 open curly brackets straight f left parenthesis 0 right parenthesis plus 4 space straight f open parentheses 1 half close parentheses plus straight f left parenthesis 1 right parenthesis close curly brackets space equals space 1 over 6 open curly brackets straight a plus 4 open parentheses straight a plus straight b over 2 plus straight c over 4 close parentheses plus left parenthesis straight a plus straight b plus straight c right parenthesis close curly brackets
               equals 1 over 6 left curly bracket straight a plus 4 straight a plus 2 straight b plus straight c plus straight a plus straight b plus straight c right curly bracket space equals space 1 over 6 left parenthesis 6 straight a plus 3 straight b plus 2 straight c right parenthesis space equals space straight a plus straight b over 2 plus straight c over 3
    straight L. straight H. straight S. space equals space integral subscript 0 superscript 1 straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript 1 left parenthesis straight a plus bx plus cx squared right parenthesis space dx space equals space open square brackets ax plus bx squared over 2 plus cx cubed over 3 close square brackets subscript 0 superscript 1
               equals space open parentheses straight a plus straight b over 2 plus straight c over 3 close parentheses space minus space left parenthesis 0 plus 0 plus 0 right parenthesis space equals space straight a plus straight b over 2 plus straight c over 3
    ∴ L.H.S. = R.H.S. Hence the result.

    Sponsor Area

    Question 80
    CBSEENMA12032430

    Prove the following:
    integral subscript 0 superscript 1 sin to the power of negative 1 end exponent straight x space dx space equals space straight pi over 2 minus 1

    Solution

    Let I = integral subscript 0 superscript 1 sin to the power of negative 1 end exponent straight x space dx space equals space integral subscript 0 superscript 1 sin to the power of negative 1 end exponent straight x.1 dx space equals space left square bracket sin to the power of negative 1 end exponent straight x. space straight x right square bracket subscript 0 superscript 1 space minus space integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 minus straight x squared end root end fraction. straight x space dx
             equals space left square bracket space straight x space sin to the power of negative 1 end exponent space straight x right square bracket subscript 0 superscript 1 space plus space 1 half integral subscript 0 superscript 1 left parenthesis 1 minus straight x squared right parenthesis to the power of negative 1 half end exponent left parenthesis negative 2 straight x right parenthesis space dx
              equals space open square brackets straight x space sin to the power of negative 1 end exponent space straight x close square brackets subscript 0 superscript 1 space plus 1 half open square brackets fraction numerator left parenthesis 1 minus straight x squared right parenthesis to the power of begin display style 1 half end style end exponent over denominator begin display style 1 half end style end fraction close square brackets subscript 0 superscript 1 space equals space left square bracket straight x space sin to the power of negative 1 end exponent space straight x right square bracket subscript 0 superscript 1 space plus space open square brackets square root of 1 minus straight x squared end root close square brackets subscript 0 superscript 1
               equals left parenthesis sin to the power of negative 1 end exponent 1 minus 0 right parenthesis space plus space left square bracket 0 minus 1 right square bracket space equals space straight pi over 2 minus 1

    Question 81
    CBSEENMA12032432

    Prove the following:
    integral subscript 1 superscript 3 fraction numerator dx over denominator straight x squared left parenthesis straight x plus 1 right parenthesis end fraction space equals space 2 over 3 plus log 2 over 3


    Solution

    Let I = integral subscript 1 superscript 3 fraction numerator 1 over denominator straight x squared left parenthesis straight x plus 1 right parenthesis end fraction dx
    Put fraction numerator 1 over denominator straight x squared left parenthesis straight x plus 1 right parenthesis end fraction space equals space straight A over straight x plus straight B over straight x squared plus fraction numerator straight C over denominator straight x plus 1 end fraction
    Multiplying both sides by x2 (x + 1), we get,
    1 ≡ A x (x + 1) + B (x + 1) + C x2    ...(1)
    Putting x = 0 in (1), we get,
    1 = B, ∴ B = 1
    Putting x + 1 = 0 or x = – 1 in (1), we get,
    1 = C (– 1 )2, ∴ C = 1
    (1) can be written as
    1 ≡ A (x+ x) + B(x + 1) + C x2    ...(2)
    Equating coeffs. in (2) of x2, we get,
    A + C = 0 ⇒ A + 1 = 0 ⇒ A = – 1
    therefore     fraction numerator 1 over denominator straight x squared left parenthesis straight x plus 1 right parenthesis end fraction space equals space 1 over straight x plus 1 over straight x squared plus fraction numerator 1 over denominator straight x plus 1 end fraction
    therefore   I = integral subscript 1 superscript 3 open parentheses negative 1 over straight x plus 1 over straight x squared plus fraction numerator 1 over denominator straight x plus 1 end fraction close parentheses dx space equals space integral subscript 1 superscript 3 open parentheses negative 1 over straight x plus straight x to the power of negative 2 end exponent plus fraction numerator 1 over denominator straight x plus 1 end fraction close parentheses dx
    space equals open square brackets negative logx plus fraction numerator straight x to the power of negative 1 end exponent over denominator negative 1 end fraction plus log left parenthesis straight x plus 1 right parenthesis close square brackets subscript 1 superscript 3 space equals space open square brackets negative logx minus 1 over straight x plus log left parenthesis straight x plus 1 right parenthesis close square brackets subscript 1 superscript 3
equals open parentheses negative log 3 minus 1 third plus log space 4 close parentheses space minus space left parenthesis negative log space 1 space minus space 1 space plus space log space 2 right parenthesis
equals negative log 3 minus 1 third plus log space 4 space plus space 1 space minus log 2 equals 2 over 3 plus log open parentheses fraction numerator 4 over denominator 3 cross times 2 end fraction close parentheses space equals space 2 over 3 plus log 2 over 3

    Question 82
    CBSEENMA12032434

    Prove the following:
    integral subscript 0 superscript straight pi over 4 end superscript space 2 space tan cubed straight x space dx space equals space 1 minus log space 2.



    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space 2 space tan cubed straight x space dx space equals space 2 integral subscript 0 superscript straight pi over 4 end superscript tanx. space tan squared straight x space dx space equals space 2 space integral subscript 0 superscript straight pi over 4 end superscript tan space straight x left parenthesis sec squared straight x minus 1 right parenthesis space dx
           equals space 2 space integral subscript 0 superscript straight pi over 4 end superscript space tanx space sec squared straight x space dx space minus space 2 integral subscript 0 superscript straight pi over 4 end superscript space tanx space dx space equals space 2 open square brackets fraction numerator tan squared straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 4 end superscript plus 2 open square brackets log open vertical bar cos space straight x close vertical bar close square brackets subscript 0 superscript straight pi over 4 end superscript
            equals space open parentheses tan squared straight pi over 4 minus tan squared 0 close parentheses space plus space 2 open square brackets log space open vertical bar cos space straight pi over 4 close vertical bar minus log open vertical bar cos space 0 close vertical bar close square brackets
            equals space open vertical bar 1 minus 0 close vertical bar space plus space 2 open parentheses log space fraction numerator 1 over denominator square root of 2 end fraction minus log space 1 close parentheses space equals space 1 plus 2 space left parenthesis log space 1 space minus space log space square root of 2 minus log space 1 right parenthesis
equals space 1 minus 2 space log space square root of 2 space equals space 1 minus log left parenthesis square root of 2 right parenthesis squared space equals space 1 minus log space 2.

    Question 83
    CBSEENMA12032436

    Prove the following:
    integral subscript 0 superscript 1 square root of fraction numerator 1 minus straight x over denominator 1 plus straight x end fraction dx end root space equals space straight pi over 2 minus 1.




    Solution

    Let I = integral subscript 0 superscript 1 square root of fraction numerator 1 minus straight x over denominator 1 plus straight x end fraction end root dx space equals space integral subscript 0 superscript 1 square root of fraction numerator 1 minus straight x over denominator 1 plus straight x end fraction cross times fraction numerator 1 minus straight x over denominator 1 minus straight x end fraction end root dx
             equals space integral subscript 0 superscript 1 fraction numerator 1 minus straight x over denominator square root of 1 minus straight x squared end root end fraction dx space equals space integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 minus straight x squared end root end fraction dx space minus space integral subscript 0 superscript 1 fraction numerator straight x over denominator square root of 1 minus straight x squared end root end fraction dx
equals space integral subscript 0 superscript 1 fraction numerator 1 over denominator square root of 1 minus straight x squared end root end fraction dx plus 1 half integral subscript 0 superscript 1 left parenthesis 1 minus straight x squared right parenthesis space to the power of 1 half end exponent left parenthesis negative 2 straight x right parenthesis space dx
      equals space open square brackets sin to the power of negative 1 end exponent straight x close square brackets subscript 0 superscript 1 space plus space 1 half open square brackets fraction numerator left parenthesis 1 minus straight x squared right parenthesis to the power of begin display style 1 half end style end exponent over denominator begin display style 1 half end style end fraction close square brackets subscript 0 superscript 1 space equals space open square brackets sin to the power of negative 1 end exponent straight x close square brackets subscript 0 superscript 1 plus open square brackets square root of 1 minus straight x squared end root close square brackets subscript 0 superscript 1
     =left parenthesis sin to the power of negative 1 end exponent 1 minus sin to the power of negative 1 end exponent 0 right parenthesis space plus space left parenthesis square root of 1 minus 1 end root space minus space square root of 1 minus 0 right parenthesis end root space equals space straight pi over 2 minus 0 plus 0 minus 1 space equals space straight pi over 2 minus 1.

    Question 84
    CBSEENMA12032438

    integral subscript 1 superscript square root of 3 end superscript fraction numerator dx over denominator 1 plus straight x squared end fraction equals

    • straight pi over 3
    • fraction numerator 2 straight pi over denominator 3 end fraction
    • straight pi over 6
    • straight pi over 12

    Solution

    D.

    straight pi over 12

    Let I = integral subscript 1 superscript square root of 3 end superscript fraction numerator 1 over denominator 1 plus straight x squared end fraction dx space equals space open square brackets tan to the power of negative 1 end exponent straight x close square brackets subscript 1 superscript square root of 3 end superscript
            equals space tan to the power of negative 1 end exponent square root of 3 space minus space tan to the power of negative 1 end exponent 1 space equals space straight pi over 3 minus straight pi over 4 space equals space fraction numerator 4 straight pi minus 3 straight pi over denominator 12 end fraction equals straight pi over 12

    Question 85
    CBSEENMA12032439

    integral subscript 0 superscript 2 over 3 end superscript fraction numerator dx over denominator 4 plus 9 straight x squared end fraction space equals
    • straight pi over 6
    • straight pi over 12
    • straight pi over 24
    • straight pi over 4

    Solution

    C.

    straight pi over 24

    Let 
    I = integral subscript 0 superscript 2 over 3 end superscript fraction numerator dx over denominator 4 plus 9 straight x squared end fraction space equals space 1 over 9 integral subscript 0 superscript 2 over 3 end superscript fraction numerator 1 over denominator begin display style 4 over 9 end style plus straight x squared end fraction dx space equals space 1 over 9 integral subscript 0 superscript 2 over 3 end superscript fraction numerator 1 over denominator open parentheses begin display style 2 over 3 end style close parentheses squared plus straight x squared end fraction dx
        equals space 1 over 9. fraction numerator 1 over denominator begin display style 2 over 3 end style end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight x over denominator begin display style 2 over 3 end style end fraction close parentheses close square brackets subscript 0 superscript 2 over 3 end superscript space equals space 1 over 6 open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator 3 straight x over denominator 2 end fraction close parentheses close square brackets subscript 0 superscript 2 over 3 end superscript
equals space 1 over 6 left parenthesis tan to the power of negative 1 end exponent space 1 space minus space tan to the power of negative 1 end exponent 0 right parenthesis space equals space 1 over 6 open parentheses straight pi over 4 minus 0 close parentheses space equals space straight pi over 24

    Question 86
    CBSEENMA12032441

    Evaluate integral subscript 0 superscript 2 straight pi end superscript fraction numerator cosx over denominator square root of 4 plus 3 sinx end root end fraction dx.

    Solution

    Let I = integral subscript 0 superscript 2 straight pi end superscript fraction numerator cos space straight x over denominator square root of 4 plus 3 space sinx end root end fraction dx
    Put 4 plus 3 space sinx equals space straight y comma space space space space therefore space space 3 space cosx space dx space equals space dy space space space space rightwards double arrow space space space cosxdx space equals space 1 third dy
    When x = 0, y = 4 + 3 sin 0 = 4 + 0 = 4
    When x = 2 straight pi, y = 4 + 3 sin 2 straight pi = 4 + 3 x 0 = 4 + 0 = 4
    therefore      straight I space equals space 1 third integral subscript 4 superscript 4 fraction numerator 1 over denominator square root of straight y end fraction dy space equals space 1 third integral subscript 4 superscript 4 straight y to the power of negative 1 half end exponent dy space equals space 1 third open square brackets fraction numerator straight y to the power of begin display style 1 half end style end exponent over denominator begin display style 1 half end style end fraction close square brackets subscript 4 superscript 4 space equals space 2 over 3 open square brackets square root of straight y close square brackets subscript 4 superscript 4 space equals space 2 over 3 left parenthesis 2 minus 2 right parenthesis space equals space 2 over 3 cross times 0 space equals 0

    Question 87
    CBSEENMA12032443

    Evaluate integral subscript 0 superscript straight pi over 6 end superscript left parenthesis 1 minus cos space 3 straight theta right parenthesis space sin space 3 straight theta space dθ

    Solution

    Let I = integral subscript 0 superscript straight pi over 6 end superscript left parenthesis 1 minus cos space 3 straight theta right parenthesis space sin space 3 straight theta space dθ
    Put 1 minus cos space 3 straight theta space equals space straight y comma space space therefore space space space 3 space sin space 3 straight theta space dθ space equals space dy space rightwards double arrow space space space sin space 3 straight theta space dθ space equals space 1 third dy
    When straight theta space equals space 0 comma space space space straight y space equals space 1 minus cosθ space equals space 1 minus 1 space equals space 0
    When  straight theta space equals space straight pi over 6 comma space straight y space equals space 1 minus cos straight pi over 2 space equals space 1 minus 0 space equals space 1
    therefore          1 space equals 1 third integral subscript 0 superscript 1 ydy space equals space 1 third open square brackets straight y squared over 2 close square brackets subscript 0 superscript 1 space equals space 1 over 6 left square bracket straight y squared right square bracket subscript 0 superscript 1 space equals space 1 over 6 left parenthesis 1 minus 0 right parenthesis space equals space 1 over 6

    Question 88
    CBSEENMA12032445

    Evaluate integral subscript 0 superscript straight pi space 5 space left parenthesis 5 minus 4 space cosθ right parenthesis to the power of 1 fourth end exponent space sin space straight theta space dθ

    Solution

    Let I = integral subscript 0 superscript straight pi 5 space left parenthesis 5 minus 4 cosθ right parenthesis to the power of 1 fourth end exponent space sin space straight theta space dθ space equals space 5 integral subscript 0 superscript straight pi left parenthesis 5 minus 4 space cosθ right parenthesis to the power of 1 fourth end exponent space sin space straight theta space dθ
    Put 5 minus 4 space cosθ space equals space straight y comma space space therefore space space 4 space sin space straight theta space dθ space equals space dy space rightwards double arrow space space space sin space straight theta space dθ space equals space 1 fourth dy
    When straight theta space equals 0 comma space space straight y space equals space 5 minus 4 space cos space 0 space equals space 5 minus 4 space equals space 1
    When straight theta space equals space straight pi comma space space straight y space equals space 5 minus 4 space cosπ space equals space 5 minus 4 left parenthesis negative 1 right parenthesis space equals space 5 plus 4 space equals space 9
    therefore    I = 5 over 4 integral subscript 1 superscript 9 straight y to the power of 1 fourth end exponent dy space equals space 5 over 4 open square brackets fraction numerator straight y to the power of begin display style 5 over 4 end style end exponent over denominator begin display style 5 over 4 end style end fraction close square brackets subscript 1 superscript 9 space equals space open square brackets straight y to the power of 5 over 4 end exponent close square brackets subscript 1 superscript 9                                     equals left parenthesis 9 right parenthesis to the power of 5 over 4 end exponent minus 1 space equals space left parenthesis 3 squared right parenthesis to the power of 5 over 4 end exponent minus 1 space equals space 3 to the power of 5 over 2 end exponent minus 1 space equals space left parenthesis 3 to the power of 5 right parenthesis to the power of 1 half end exponent minus 1 space equals space left parenthesis 81 cross times 3 right parenthesis to the power of 1 half end exponent minus 1 space equals space 9 square root of 3 minus 1

    Question 89
    CBSEENMA12032448

    Evaluate  integral subscript 0 superscript straight pi over 6 end superscript space cos to the power of negative 3 end exponent 2 straight theta space sin space 2 straight theta space dθ

    Solution

    Let I = integral subscript 0 superscript straight pi over 6 end superscript space cos to the power of negative 3 end exponent 2 straight theta space sin 2 straight theta space space dθ space equals space integral subscript 0 superscript straight pi over 6 end superscript fraction numerator sin space 2 straight theta space dθ over denominator cos cubed space 2 straight theta end fraction
    Put cos space 2 straight theta space equals space straight y comma space space therefore space space minus 2 space sin space 2 straight theta space dθ space equals space dy space space space rightwards double arrow space space sin space 2 straight theta space dθ space equals space minus 1 half dy
    When straight theta space equals space 0 comma space space straight y space equals space cos space 0 space equals space 1
    When straight theta space equals space straight pi over 6 comma space space space straight y space equals space cos straight pi over 3 space equals space 1 half
    therefore        straight I space equals space minus 1 half integral subscript 1 superscript 1 half end superscript 1 over straight y cubed dy space equals space minus 1 half integral subscript 1 superscript 1 half end superscript straight y to the power of negative 3 end exponent space dy space equals space minus 1 half open square brackets fraction numerator straight y to the power of negative 2 end exponent over denominator negative 2 end fraction close square brackets to the power of 1 half end exponent
                    equals space 1 fourth open square brackets 1 over straight y squared close square brackets subscript 1 superscript 1 half end superscript space equals space 1 fourth left square bracket 4 minus 1 right square bracket space equals space 1 fourth cross times 3 space equals space 3 over 4

    Question 90
    CBSEENMA12032451

    Evaluate  space integral subscript 0 superscript 3 square root of straight pi squared end root end superscript square root of straight x space cos squared open parentheses straight x to the power of 3 over 2 end exponent close parentheses dx.

    Solution

    Let I = integral subscript 0 superscript cube root of straight pi squared end root end superscript square root of straight x space cos squared open parentheses straight x to the power of 3 over 2 end exponent close parentheses dx
    Put straight x to the power of 3 over 2 end exponent space equals space straight y comma space space space space therefore space space space 3 over 2 straight x to the power of 1 half end exponent space equals space dy space space space space rightwards double arrow space space space space space square root of straight x space dx space equals space 2 over 3 dy
    When x = 0,  y = 0
    When  straight x equals space left parenthesis straight pi squared right parenthesis to the power of 1 third end exponent space straight y space equals space open square brackets open parentheses straight pi squared close parentheses to the power of 1 third end exponent close square brackets to the power of 3 over 2 end exponent space equals space open parentheses straight pi to the power of 2 over 3 end exponent close parentheses to the power of 3 over 2 end exponent space equals space straight pi
    therefore        I = 2 over 3 integral subscript 0 superscript straight pi cos squared space straight y space dy space equals space 1 third integral subscript 0 superscript straight pi left parenthesis 2 space cos squared space straight y right parenthesis dy space equals space 1 third integral subscript 0 superscript straight pi left parenthesis 1 plus cos space 2 straight y right parenthesis space dy
                  equals space 1 third open square brackets straight y plus fraction numerator sin space 2 straight y over denominator 2 end fraction close square brackets subscript 0 superscript straight pi space equals space 1 third open square brackets open parentheses straight pi plus fraction numerator sin space 2 straight pi over denominator 2 end fraction close parentheses minus open parentheses 0 plus fraction numerator sin space 0 over denominator 2 end fraction close parentheses close square brackets
equals space 1 third open square brackets open parentheses straight pi plus 0 over 2 close parentheses minus open parentheses 0 plus 0 over 2 close parentheses close square brackets space equals space 1 third left square bracket straight pi right square bracket space equals space space straight pi over 3

    Question 91
    CBSEENMA12032453

    Evaluate the following integral using substitution.
    integral subscript 0 superscript 1 fraction numerator straight x over denominator straight x squared plus 1 end fraction dx

    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator straight x over denominator straight x squared plus 1 end fraction dx
    Put straight x squared plus 1 space equals space straight y semicolon space space space space space space therefore space space 2 straight x space dx space equals space dy semicolon space space space space or space straight x space dx space equals space 1 half dy
    When x = 2,  y = 5
    When x = 3,  y = 10
    therefore space space space straight I space space equals space 1 half integral subscript 5 superscript 10 dy over straight y space equals space 1 half open square brackets log space straight y close square brackets subscript 5 superscript 10 space equals space 1 half left square bracket log space 10 minus space log space 5 right square bracket space equals space 1 half log open parentheses 10 over 5 close parentheses space equals space 1 half log 2

    Question 92
    CBSEENMA12032456

    Evaluate the following integral using substitution.



    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator straight e to the power of straight x over denominator 1 plus straight e to the power of 2 straight x end exponent end fraction dx
    Put   straight e to the power of straight x space equals space straight y comma space space space space space space space space space space space space therefore space space straight e to the power of straight x dx space equals space dy
    When straight x equals space 0 comma space space space space space straight y space equals space straight e to the power of 0 space equals space 1
    When straight x space equals space 1 comma space space space space straight y space equals space straight e to the power of 1 space equals space straight e
    therefore space space space space space space straight I space equals space integral subscript 1 superscript straight e fraction numerator 1 over denominator 1 plus straight y squared end fraction dy space equals space open square brackets tan to the power of negative 1 end exponent space straight y close square brackets subscript 1 superscript straight e space equals space tan to the power of negative 1 end exponent straight e minus tan to the power of negative 1 end exponent 1 space equals space tan to the power of negative 1 end exponent open parentheses fraction numerator straight e minus 1 over denominator 1 plus straight e end fraction close parentheses

    Question 93
    CBSEENMA12032460

    Evaluate the following definite integral:
    integral subscript 0 superscript 1 straight x space straight e to the power of straight x squared end exponent space dx



    Solution

    Let I = integral subscript 0 superscript 1 straight x. straight e to the power of straight x squared end exponent dx
    Put straight x squared space equals space straight y semicolon space space space space space space space space space space therefore space 2 space straight x space dx space equals space dy space space space space space space space space space rightwards double arrow space space space straight x space dx space equals space 1 half dy
    When x = 0, y = 0
    When x = 1, y = 1
    therefore space space space space space straight I space equals space 1 half integral subscript 0 superscript 1 straight e to the power of straight y space dy space equals space 1 half left square bracket straight e to the power of straight y right square bracket subscript 0 superscript 1 space equals space 1 half left parenthesis straight e to the power of 1 minus straight e to the power of 0 right parenthesis space equals space 1 half left parenthesis straight e minus 1 right parenthesis

    Question 94
    CBSEENMA12032464

    Evaluate the following definite integral:
    integral subscript 1 superscript 2 fraction numerator 1 over denominator straight x left parenthesis 1 plus log space straight x right parenthesis squared end fraction dx




    Solution

    Let I = integral subscript 1 superscript 2 fraction numerator 1 over denominator straight x left parenthesis 1 plus log space straight x right parenthesis squared end fraction dx
    Put log x = y;    therefore space space 1 over straight x space dx space equals space dy
    When x = 1,    y = log 1 = 0
    When x = 2,    y = log 2
    therefore     I = integral subscript 0 superscript log space 2 end superscript fraction numerator 1 over denominator left parenthesis 1 plus straight y right parenthesis squared end fraction dy space equals space integral subscript 0 superscript log space 2 end superscript left parenthesis 1 plus straight y right parenthesis to the power of negative 2 end exponent space dy space equals space open square brackets fraction numerator left parenthesis 1 plus straight y right parenthesis to the power of negative 1 end exponent over denominator negative 1 end fraction close square brackets subscript 0 superscript log space 2 end superscript
                equals negative open square brackets fraction numerator 1 over denominator 1 plus straight y end fraction close square brackets subscript 0 superscript log 2 end superscript space equals space minus open parentheses fraction numerator 1 over denominator 1 plus log 2 end fraction minus 1 close parentheses space equals space 1 minus fraction numerator 1 over denominator 1 plus log 2 end fraction equals space fraction numerator log space 2 over denominator 1 plus log 2 end fraction

    Question 95
    CBSEENMA12032467

    Evaluate the following integral using substitution
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x over denominator 1 plus cos squared straight x end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx space over denominator 1 plus cos squared straight x end fraction dx
    Put cos x = t, ∴ sin x dx = dt ⇒ sin x dx = – dt When x = 0, t = cos 0 = 1
    When x = straight pi over 2 comma space space straight t space equals space cos straight pi over 2 space equals space 0
    therefore space space space space space space straight I space equals space minus integral subscript 1 superscript 0 fraction numerator dt over denominator 1 plus straight t squared end fraction space equals space minus left square bracket tan to the power of negative 1 end exponent straight t right square bracket subscript 1 superscript 0 space equals space minus left square bracket tan to the power of negative 1 end exponent 0 minus tan to the power of negative 1 end exponent 1 right square bracket space equals space minus open square brackets 0 minus straight pi over 4 close square brackets space equals space straight pi over 4

    Question 96
    CBSEENMA12032469

    Evaluate the following integral:
    integral subscript straight pi over 6 end subscript superscript straight pi over 2 end superscript fraction numerator cosec space straight x space cotx over denominator 1 minus cosec squared straight x end fraction dx


    Solution

    Let I = integral subscript straight pi over 6 end subscript superscript straight pi over 2 end superscript fraction numerator cosecx space cosx over denominator 1 plus cosec squared straight x end fraction dx
    Put cosec x = y,    therefore space space space space minus cosecx space cot space straight x space dx space equals space dy         rightwards double arrow space space cosec space straight x space cotx space dx space equals space minus dy
    When straight x equals straight pi over 6 comma space space space space space straight y space equals space cosec straight pi over 6 space equals space 2
    When straight x equals straight pi over 2      straight y equals cosec straight pi over 2 space equals space 1
    therefore space space space straight I space equals space space integral subscript 2 superscript 1 fraction numerator 1 over denominator 1 plus straight y squared end fraction dy space equals space minus open square brackets tan to the power of negative 1 end exponent space straight y close square brackets subscript 2 superscript 1 space equals space minus left parenthesis tan to the power of negative 1 end exponent 1 space minus space tan to the power of negative 1 end exponent 2 right parenthesis space equals space tan to the power of negative 1 end exponent 2 space minus space tan to the power of negative 1 end exponent 1
               equals space tan to the power of negative 1 end exponent open parentheses fraction numerator 2 minus 1 over denominator 1 plus 2 end fraction close parentheses space equals space tan to the power of negative 1 end exponent 1 third

    Question 97
    CBSEENMA12032472

    Evaluate the following integral:
    integral subscript 1 superscript 2 1 over straight x squared straight e to the power of negative 1 over straight x end exponent dx



    Solution

    Let I = integral subscript 1 superscript 2 1 over straight x squared straight e to the power of 1 over straight x end exponent dx
    Put 1 over straight x space equals straight y comma space space space space space space therefore space space minus 1 over straight x squared dx space equals space dy space space space space space space space space space space rightwards double arrow space space space 1 over straight x squared dx space space equals negative dy
    When x = 1,   y = 1
    When x  =2,   y = 1 half
    therefore space space space straight I space space equals negative integral subscript 1 superscript 1 half end superscript space straight e to the power of straight y space dx equals space minus open square brackets straight e to the power of straight y close square brackets subscript 1 superscript 1 half end superscript space equals space minus open square brackets straight e to the power of 1 half end exponent minus straight e to the power of 1 close square brackets space equals space straight e minus square root of straight e

    Question 98
    CBSEENMA12032475

    Evaluate the following integral:
    integral subscript 0 superscript 1 fraction numerator left parenthesis tan to the power of negative 1 end exponent straight x right parenthesis squared over denominator 1 plus straight x squared end fraction dx




    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator left parenthesis tan to the power of negative 1 end exponent straight x right parenthesis squared over denominator 1 plus straight x squared end fraction dx
    Put tan to the power of negative 1 end exponent straight x space equals space straight y comma space space space space space therefore space space space space fraction numerator 1 over denominator 1 plus straight x squared end fraction dx space equals space dy
    When x = 0,  straight y space equals tan to the power of negative 1 end exponent 0 space equals space 0
    When x = 1,  straight y space equals space tan to the power of negative 1 end exponent space 1 space space equals space straight pi over 4
    therefore       straight I space equals space integral subscript 0 superscript straight pi over 4 end superscript space straight y squared dy space equals space open square brackets straight y cubed over 3 close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space 1 third open square brackets straight pi cubed over 64 minus 0 close square brackets space equals space straight pi cubed over 192

    Question 99
    CBSEENMA12032477

    Evaluate the following integral using substitution.
    integral subscript 0 superscript 2 straight x space square root of straight x plus 2 end root dx.





    Solution

    Let I = integral subscript 0 superscript 2 straight x square root of straight x plus 2 end root dx
    Put square root of straight x plus 2 end root space equals space straight y space space or space space straight x plus 2 space equals space straight y squared space space space space space space rightwards double arrow space space space space straight x space equals space straight y squared minus 2
    therefore space space space space dx space equals space 2 space straight y space dy
    When x = 0,  straight y equals square root of 0 plus 2 end root space equals space square root of 2
    When x = 2,   straight y space equals space square root of 2 plus 2 end root space equals space square root of 4 space equals space 2
    therefore space space space space straight I space equals space integral subscript square root of 2 end subscript superscript 2 space left parenthesis straight y squared minus 2 right parenthesis. space straight y space. space 2 space straight y space dy space equals space 2 integral subscript square root of 2 end subscript superscript 2 space left parenthesis straight y squared minus 2 right parenthesis. space straight y squared space dy
              equals space 2 integral subscript square root of 2 end subscript superscript 2 left parenthesis straight y to the power of 4 minus 2 straight y squared right parenthesis space dy space equals space 2 open square brackets straight y to the power of 5 over 5 minus 2 over 3 straight y cubed close square brackets subscript square root of 2 end subscript superscript 2
               space equals space 2 open square brackets open parentheses 32 over 5 minus 16 over 3 close parentheses minus open parentheses fraction numerator 4 square root of 2 over denominator 5 end fraction minus fraction numerator 4 square root of 2 over denominator 3 end fraction close parentheses close square brackets space equals space 2 open square brackets fraction numerator 96 minus 80 over denominator 15 end fraction minus fraction numerator 12 square root of 2 minus 20 square root of 2 over denominator 15 end fraction close square brackets
                = 2 open square brackets 16 over 15 plus fraction numerator 8 square root of 2 over denominator 15 end fraction close square brackets space equals space 16 over 15 left parenthesis 2 plus square root of 2 right parenthesis

    Question 100
    CBSEENMA12032478

    Evaluate integral subscript negative 1 end subscript superscript 1 5 straight x to the power of 4 square root of straight x to the power of 5 plus 1 end root dx.

    Solution

    Let I = integral subscript negative 1 end subscript superscript 1 left parenthesis straight x to the power of 5 plus 1 right parenthesis to the power of 1 half end exponent left parenthesis 5 straight x to the power of 4 right parenthesis space dx
    Put x5 + 1 = y, ∴ 5 x4 dx = dy When x = –1 , y = – 1 + 1 = 0 When x = 1, y = 1 + 1 = 2
    therefore       straight I space equals space integral subscript 0 superscript 2 straight y to the power of 1 half end exponent dy space equals space open square brackets fraction numerator straight y to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction close square brackets subscript 0 superscript 2 space equals space 2 over 3 open square brackets straight y to the power of 3 over 2 end exponent close square brackets subscript 0 superscript 2 space equals space 2 over 3 open parentheses 2 to the power of 3 over 2 end exponent minus 0 close parentheses space equals space 2 over 3 open parentheses 2 square root of 2 close parentheses space equals space fraction numerator 4 square root of 2 over denominator 3 end fraction

    Question 101
    CBSEENMA12032479

    Evaluate the following integrals
    integral subscript negative 1 end subscript superscript 1 space straight x cubed space left parenthesis straight x to the power of 4 plus 1 right parenthesis cubed space dx

    Solution

    Let I = integral subscript negative 1 end subscript superscript 1 straight x cubed left parenthesis straight x to the power of 4 plus 1 right parenthesis cubed dx space equals space integral subscript negative 1 end subscript superscript 1 left parenthesis straight x to the power of 4 plus 1 right parenthesis cubed space straight x cubed dx
    Put straight x to the power of 4 plus 1 space equals space straight y comma space space space space space therefore space space space space 4 space straight x cubed space dx space space equals dy space space space space space space rightwards double arrow space space space space straight x cubed dx space equals space 1 fourth dy
    When x = – 1, y = 1 + 1 = 2 When x = 1, y = 1 + 1 = 2
    therefore space space space space space straight I space equals space 1 fourth integral subscript 2 superscript 2 straight y cubed dy space equals 1 fourth open square brackets straight y to the power of 4 over 4 close square brackets subscript 2 superscript 2 space equals space 1 over 16 open square brackets straight y to the power of 4 close square brackets subscript 2 superscript 2 space equals space 1 over 16 left square bracket 16 minus 16 right square bracket space equals space 1 over 16 cross times 0 space equals space 0

    Question 102
    CBSEENMA12032482

    Evaluate the following integrals
    integral subscript 0 superscript 1 straight x square root of 1 minus straight x squared end root dx

    Solution

    Let I = integral subscript 0 superscript 1 straight x square root of 1 minus straight x squared end root space dx space equals space integral subscript 0 superscript 1 left parenthesis 1 minus straight x squared right parenthesis to the power of 1 half end exponent. space straight x space dx
    Put 1 minus straight x squared space equals space straight y comma space space space space space therefore space space space minus 2 space straight x space dx space equals space dy space space space space rightwards double arrow space space space straight x space dx space equals space minus 1 half dy
    When x = 0, y = 1 – 0 = 1 When x = 1, y = 1 – 1 = 0
    therefore     I = negative 1 half integral subscript 1 superscript 0 straight y to the power of 1 half end exponent dy space equals space minus 1 half open square brackets fraction numerator straight y to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction close square brackets subscript 1 superscript 0 space equals space minus 1 third open square brackets straight y to the power of 3 over 2 end exponent close square brackets subscript 1 superscript 0 space equals space minus 1 third left square bracket 0 minus 1 right square bracket space equals space 1 third

    Question 103
    CBSEENMA12032484

    Evaluate the following integrals:
    integral subscript negative 1 end subscript superscript 1 fraction numerator 5 straight x over denominator left parenthesis 4 plus straight x squared right parenthesis squared end fraction dx



    Solution

    Let I = integral subscript negative 1 end subscript superscript 1 fraction numerator 5 straight x over denominator left parenthesis 4 plus straight x squared right parenthesis squared end fraction dx space equals space 5 integral subscript 1 superscript 1 fraction numerator straight x over denominator left parenthesis 4 plus straight x squared right parenthesis squared end fraction dx
    Put 4 plus straight x squared space equals space straight y semicolon space space space space space therefore 2 space straight x space dx space equals space dy space space space rightwards double arrow space space space straight x space dx space equals space 1 half dy
    When x = – 1, y = 4 + 1 = 5 When x = 1, y = 4 + 1 = 5
    therefore space space space straight I space equals space 5 over 2 integral subscript 5 superscript 5 1 over straight y squared dy space equals space 5 over 2 integral subscript 5 superscript 5 straight y to the power of negative 2 end exponent space equals space 5 over 2 open square brackets fraction numerator straight y to the power of negative 1 end exponent over denominator negative 1 end fraction close square brackets subscript 5 superscript 5 space equals space minus 5 over 2 open square brackets 1 fifth minus 1 fifth close square brackets space equals space minus 5 over 2 cross times 0 space equals space 0

    Question 104
    CBSEENMA12032487

    Evaluate the following integral:
    integral subscript 0 superscript 1 fraction numerator 5 straight x over denominator left parenthesis 4 plus straight x squared right parenthesis squared end fraction dx



    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator 5 straight x over denominator left parenthesis 4 plus straight x squared right parenthesis squared end fraction dx space equals space 5 integral subscript 0 superscript 1 fraction numerator straight x over denominator left parenthesis 4 plus straight x squared right parenthesis squared end fraction dx
    Put 4 plus straight x squared space equals space straight y semicolon space space space space space therefore space 2 space straight x space dx space equals space dy space rightwards double arrow space space space straight x space dx space equals space 1 half dy
    When     x = 0,  y = 4 + 0 = 4
    therefore              I = 5 over 2 integral subscript 4 superscript 5 1 over straight y squared dy space equals space 5 over 2 integral subscript 2 superscript 5 straight y to the power of negative 2 end exponent dy space equals space 5 over 2 open parentheses fraction numerator straight y to the power of negative 1 end exponent over denominator negative 1 end fraction close parentheses subscript 4 superscript 5
                       equals negative 5 over 2 open square brackets 1 over straight y close square brackets subscript 4 superscript 5 space equals space minus 5 over 2 open square brackets 1 fifth minus 1 fourth close square brackets space equals space minus 5 over 2 open square brackets fraction numerator 4 minus 5 over denominator 20 end fraction close square brackets equals negative 5 over 2 cross times fraction numerator negative 1 over denominator 20 end fraction equals space 1 over 8 

    Question 105
    CBSEENMA12032490

    Evaluate the following integral:
    integral subscript 0 superscript 2 fraction numerator dx over denominator straight x plus 4 minus straight x squared end fraction



    Solution

    Let I = integral subscript 0 superscript 2 fraction numerator dx over denominator straight x plus 4 minus straight x squared end fraction space equals space integral subscript 0 superscript 2 fraction numerator dx over denominator 4 minus left parenthesis straight x squared minus straight x right parenthesis end fraction.
          equals space integral subscript 0 superscript 2 fraction numerator dx over denominator straight x plus 4 minus straight x squared end fraction space equals space integral subscript 0 superscript 2 fraction numerator dx over denominator 4 minus left parenthesis straight x squared minus straight x right parenthesis end fraction
equals space integral subscript 0 superscript 2 fraction numerator dx over denominator open parentheses 4 plus begin display style 1 fourth end style close parentheses minus open parentheses straight x squared minus straight x plus begin display style 1 fourth end style close parentheses end fraction space equals space integral subscript 0 superscript 2 fraction numerator dx over denominator open parentheses begin display style fraction numerator square root of 17 over denominator 2 end fraction end style close parentheses squared minus open parentheses straight x minus begin display style 1 half end style close parentheses squared end fraction
equals space fraction numerator 1 over denominator 2 cross times begin display style fraction numerator square root of 17 over denominator 2 end fraction end style end fraction open square brackets log space open vertical bar fraction numerator begin display style fraction numerator square root of 17 over denominator 2 end fraction end style plus open parentheses straight x minus begin display style 1 half end style close parentheses over denominator begin display style fraction numerator square root of 17 over denominator 2 end fraction end style minus open parentheses straight x minus begin display style 1 half end style close parentheses end fraction close vertical bar close square brackets subscript 0 superscript 2
         equals fraction numerator 1 over denominator square root of 17 end fraction open square brackets log space open curly brackets fraction numerator begin display style fraction numerator square root of 17 over denominator 2 end fraction end style plus open parentheses 2 minus begin display style 1 half end style close parentheses over denominator begin display style fraction numerator square root of 17 over denominator 2 end fraction end style minus open parentheses 2 minus begin display style 1 half end style close parentheses end fraction close curly brackets minus log open curly brackets fraction numerator begin display style fraction numerator square root of 17 over denominator 2 end fraction end style minus begin display style 1 half end style over denominator begin display style fraction numerator square root of 17 over denominator 2 end fraction end style plus begin display style 1 half end style end fraction close curly brackets close square brackets
        equals fraction numerator 1 over denominator square root of 17 end fraction open square brackets log space fraction numerator square root of 17 plus 3 over denominator square root of 17 minus 3 end fraction minus log fraction numerator square root of 17 minus 1 over denominator square root of 17 plus 1 end fraction close square brackets
equals space fraction numerator 1 over denominator square root of 17 end fraction log open square brackets fraction numerator square root of 17 plus 3 over denominator square root of 17 minus 3 end fraction cross times fraction numerator square root of 17 plus 1 over denominator square root of 17 minus 1 end fraction close square brackets space equals space fraction numerator 1 over denominator square root of 17 end fraction log open parentheses fraction numerator 17 plus 3 plus 4 square root of 17 over denominator 17 plus 3 minus 4 square root of 17 end fraction close parentheses
equals space fraction numerator 1 over denominator square root of 17 end fraction log open parentheses fraction numerator 5 plus square root of 17 over denominator 5 minus square root of 17 end fraction close parentheses space equals space fraction numerator 1 over denominator square root of 17 end fraction log open parentheses fraction numerator 5 plus square root of 17 over denominator 5 minus square root of 17 end fraction cross times fraction numerator 5 plus square root of 17 over denominator 5 plus square root of 17 end fraction close parentheses
equals space fraction numerator 1 over denominator square root of 17 end fraction log open parentheses fraction numerator 25 plus 17 plus 10 square root of 17 over denominator 25 minus 17 end fraction close parentheses equals space fraction numerator 1 over denominator square root of 17 end fraction log open parentheses fraction numerator 42 plus 10 square root of 17 over denominator 8 end fraction close parentheses
equals space fraction numerator 1 over denominator square root of 17 end fraction log open parentheses fraction numerator 21 plus 5 square root of 7 over denominator 4 end fraction close parentheses

    Question 106
    CBSEENMA12032492

    Evaluate the following integral:
    integral subscript negative 1 end subscript superscript 1 fraction numerator dx over denominator straight x squared plus 2 straight x plus 5 end fraction

    Solution

    Let I = integral subscript negative 1 end subscript superscript 1 fraction numerator 1 over denominator straight x squared plus 2 straight x plus 5 end fraction dx space equals space integral subscript negative 1 end subscript superscript 1 fraction numerator 1 over denominator left parenthesis straight x squared plus 2 straight x plus 1 right parenthesis plus 4 end fraction dx
       equals space integral subscript negative 1 end subscript superscript 1 fraction numerator 1 over denominator left parenthesis straight x plus 1 right parenthesis squared plus left parenthesis 2 right parenthesis squared end fraction dx space equals space 1 half open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight x plus 1 over denominator 2 end fraction close parentheses close square brackets subscript negative 1 end subscript superscript 1
equals space 1 half left square bracket tan to the power of negative 1 end exponent 1 space minus space tan to the power of negative 1 end exponent 0 right square bracket space equals space 1 half open parentheses straight pi over 4 minus 0 close parentheses space equals space straight pi over 8

    Question 107
    CBSEENMA12032494

    Evaluate integral subscript 0 superscript straight pi over 2 end superscript space square root of sin space straight ϕ end root space cos to the power of 5 straight ϕ space dϕ space

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript square root of sin space straight ϕ end root space cos to the power of 5 straight ϕ space dϕ space equals space integral subscript 0 superscript straight pi over 2 end superscript square root of sin space straight ϕ end root. space cos to the power of 4 straight ϕ. space cosϕ space dϕ
            equals space integral subscript 0 superscript straight pi over 2 end superscript square root of sin space straight ϕ end root. space left parenthesis cos squared straight ϕ right parenthesis squared space cos space straight ϕ space dϕ space equals space integral subscript 0 superscript straight pi over 2 end superscript square root of sin space straight ϕ end root space left parenthesis 1 minus sin squared straight ϕ right parenthesis squared. space cos space straight ϕ space dϕ
    Put sin ϕ = t,    ∴ cos ϕ dϕ = dt
    When ϕ = 0, t = sin 0 = 0
    When straight ϕ space equals space straight pi over 2 comma space straight t space equals space sin space straight pi over 2 space equals space 1
    therefore      straight I space equals space integral subscript 0 superscript 1 square root of straight t left parenthesis 1 minus straight t right parenthesis squared space dt space equals space integral subscript 0 superscript 1 straight t to the power of 1 half end exponent left parenthesis straight t to the power of 4 minus 2 straight t squared plus 1 right parenthesis space dt
                 equals space integral subscript 0 superscript 1 open parentheses straight t to the power of 9 over 2 end exponent minus 2 straight t to the power of 5 over 2 end exponent plus straight t to the power of 1 half end exponent close parentheses space dt space equals space open square brackets fraction numerator straight t to the power of begin display style 11 over 2 end style end exponent over denominator begin display style 11 over 2 end style end fraction minus 2 fraction numerator straight t to the power of begin display style 7 over 2 end style end exponent over denominator begin display style 7 over 2 end style end fraction plus fraction numerator straight t to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction close square brackets subscript 0 superscript 1
           open square brackets 2 over 11 straight t to the power of 11 over 2 end exponent minus 4 over 7 straight t to the power of 7 over 2 end exponent plus 2 over 3 straight t to the power of 3 over 2 end exponent close square brackets subscript 0 superscript 1 space equals space open square brackets open parentheses 2 over 11 minus 4 over 7 plus 2 over 3 close parentheses minus left parenthesis 0 plus 0 plus 0 right parenthesis close square brackets
                                         equals space fraction numerator 42 minus 132 plus 154 over denominator 231 end fraction equals 64 over 231

    Question 108
    CBSEENMA12032496

    Evaluate integral subscript 0 superscript 2 fraction numerator 5 straight x plus 1 over denominator straight x squared plus 4 end fraction dx.

    Solution

    Let I = integral subscript 0 superscript 2 fraction numerator 5 straight x plus 1 over denominator straight x squared plus 4 end fraction dx space equals space integral subscript 0 superscript 2 fraction numerator 5 straight x over denominator straight x squared plus 4 end fraction dx plus integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus 4 end fraction dx
    therefore                straight I space equals space straight I subscript 1 plus straight I subscript 2                                                          ...(1)
    Put straight x squared plus 4 space equals space straight y comma space space space therefore space space 2 space straight x space dx space equals space dy space space space rightwards double arrow space space space straight x space dx space equals space 1 half dy
    When x = 0, y = 0 + 4 = 4 When x = 2, y = 4 + 4 = 8
    therefore      straight I subscript 1 space equals space 5 over 2 integral subscript 4 superscript 8 1 over straight y dy space equals space 5 over 2 open square brackets log space straight y close square brackets subscript 4 superscript 8 space equals space 5 over 2 left parenthesis log space 8 space minus space log space 4 right parenthesis space equals 5 over 2 log open parentheses 8 over 4 close parentheses space equals space 5 over 2 log space 2
                straight I subscript 2 space equals space integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus 4 end fraction dx space equals space integral subscript 0 superscript 2 fraction numerator 1 over denominator straight x squared plus left parenthesis 2 right parenthesis squared end fraction dx
                       equals space 1 half open square brackets tan to the power of negative 1 end exponent open parentheses straight x over 2 close parentheses close square brackets subscript 0 superscript 2 space space equals space 1 half left square bracket tan to the power of negative 1 end exponent 1 minus tan to the power of negative 1 end exponent 0 right square bracket space equals space 1 half open square brackets straight pi over 4 minus 0 close square brackets space equals space straight pi over 8
    therefore   from (1),  straight I space equals 5 over 2 log space 2 space plus space straight pi over 8

    Question 109
    CBSEENMA12032498

    Prove that: integral subscript negative straight a end subscript superscript straight a square root of fraction numerator straight a minus straight x over denominator straight a plus straight x end fraction end root space dx space equals space straight a space straight pi.

    Solution

    Let I = integral subscript negative straight a end subscript superscript straight a space square root of fraction numerator straight a minus straight x over denominator straight a plus straight x end fraction end root dx
    Put x = a cos θ , ∴ dx = –a sin θ dθ
    When x = a, a = a cos θ ⇒ 1 = cos θ    ⇒ θ = 0
    When x = –a, –a = a cos θ ⇒ – 1 = cos θ ⇒ θ = straight pi
    therefore                               straight I space equals space integral subscript straight pi superscript 0 square root of fraction numerator straight a minus acosθ over denominator straight a plus acosθ end fraction end root space space space space left parenthesis negative straight a space sin space straight theta space dθ right parenthesis
                             equals space straight a space integral subscript 0 superscript straight pi square root of fraction numerator 1 minus cosθ over denominator 1 plus cosθ end fraction end root. space space sin space straight theta space dθ space equals space straight a space integral subscript 0 superscript straight pi square root of fraction numerator 2 sin squared begin display style straight theta over 2 end style over denominator 2 cos squared begin display style straight theta over 2 end style end fraction end root. space sin space straight theta space dθ
        equals space straight a space integral subscript 0 superscript straight pi fraction numerator sin space begin display style straight theta over 2 end style over denominator cos begin display style straight theta over 2 end style end fraction. space 2 space sin space straight theta over 2 space cos straight theta over 2 space dθ space equals space straight a space integral subscript 0 superscript straight pi space 2 space sin squared straight theta over 2 space dθ
       equals space straight a integral subscript 0 superscript straight pi left parenthesis 1 minus cos space straight theta right parenthesis dθ space equals space straight a space open square brackets straight theta minus sinθ close square brackets subscript 0 superscript straight pi
       equals space straight a open square brackets left parenthesis straight pi minus sin space straight pi right parenthesis space minus space left parenthesis 0 minus sin space 0 right parenthesis close square brackets
equals space straight a open square brackets left parenthesis straight pi minus 0 right parenthesis space minus space left parenthesis 0 minus 0 right parenthesis close square brackets space equals aπ.

    Question 110
    CBSEENMA12032499

    Evaluate  integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x space plus space cos space straight x over denominator square root of sinx space cosx end root end fraction dx.

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx plus cosx over denominator square root of sin space straight x space cosx end root end fraction dx space equals space 4 integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx plus cosx over denominator square root of 2 space sinx space cosx end root end fraction dx
           equals space 4 space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x space plus space cos space straight x over denominator square root of sin space 2 straight x end root end fraction dx space equals space 4 space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx space plus space cosx over denominator square root of 1 minus left parenthesis 1 minus sin space 2 straight x right parenthesis end root end fraction dx
           equals space 4 space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x space plus space cos space straight x over denominator square root of 1 minus left parenthesis sin squared straight x plus cos squared straight x minus 2 sinx space cosx right parenthesis end root end fraction dx
equals space 4 integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x space plus space cos space straight x space over denominator square root of 1 minus left parenthesis sinx space space minus cosx right parenthesis squared end root end fraction dx
    Put sin x - cos x = y, ∴ (cos x + sin x) dx = dy When x = 0, y = sin 0 – cos 0 = 0 – 1 = – 1
    When  straight x equals space straight pi over 2 comma space space space straight y space equals space sin straight pi over 2 minus cos straight pi over 2 space equals space 1 minus 0 space equals space 1
    therefore          straight I space equals space 4 integral subscript negative 1 end subscript superscript 1 fraction numerator 1 over denominator square root of 1 minus straight y squared end root end fraction dy space equals space 4 open square brackets sin to the power of negative 1 end exponent space straight y close square brackets subscript negative 1 end subscript superscript 1 space equals space 4 open square brackets sin to the power of negative 1 end exponent left parenthesis 1 right parenthesis space minus space sin to the power of negative 1 end exponent left parenthesis negative 1 right parenthesis close square brackets
                    equals space 4 space open square brackets straight pi over 2 minus open parentheses negative straight pi over 2 close parentheses close square brackets space equals space 4 open parentheses straight pi over 2 plus straight pi over 2 close parentheses space equals space 4 straight pi

    Question 111
    CBSEENMA12032501

    Evaluate: integral subscript 0 superscript straight pi over 4 end superscript space secx square root of fraction numerator 1 minus sin space straight x over denominator 1 plus sin space straight x end fraction end root dx.

    Solution
    straight I space equals space integral subscript 0 superscript straight pi over 4 end superscript secx square root of fraction numerator 1 minus sinx over denominator 1 plus sinx end fraction end root dx space equals space integral subscript 0 superscript straight pi over 4 end superscript secx square root of fraction numerator 1 minus sinx over denominator 1 plus sinx end fraction cross times fraction numerator 1 minus sinx over denominator 1 minus sinx end fraction end root dx
            equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 1 over denominator cos space straight x end fraction. square root of fraction numerator left parenthesis 1 minus sinx right parenthesis squared over denominator 1 minus sin squared straight x end fraction end root dx space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 1 over denominator cos space straight x end fraction. square root of fraction numerator 1 minus sinx over denominator cos squared straight x end fraction end root dx
             equals space integral subscript 0 superscript straight pi over 4 end superscript 1 over cosx. fraction numerator 1 minus sinx over denominator cosx end fraction dx space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 1 minus sinx over denominator cos squared straight x end fraction dx
             
               equals space integral subscript 0 superscript straight pi over 4 end superscript space open parentheses fraction numerator 1 over denominator cos squared straight x end fraction minus 1 over cosx cross times sinx over cosx close parentheses dx space space equals integral subscript 0 superscript straight pi over 4 end superscript left parenthesis sec squared straight x minus secx space tanx right parenthesis space dx
equals space open square brackets tanx space minus space secx close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space open parentheses tan straight pi over 4 minus sec straight pi over 4 close parentheses space minus space left square bracket tan space 0 space minus space sec space 0 right square bracket
equals space open parentheses 1 minus square root of 2 close parentheses space minus space left parenthesis 0 space minus space 1 right parenthesis space equals space 1 minus square root of 2 space plus space 1 space equals space 2 minus square root of 2
    Question 112
    CBSEENMA12032504

    Evaluate:  integral subscript 0 superscript straight a space sin to the power of negative 1 end exponent space open parentheses square root of fraction numerator straight x over denominator straight a plus straight x end fraction end root close parentheses dx.

    Solution

    Let 
    straight I space equals space integral subscript 0 superscript straight a space sin to the power of negative 1 end exponent open parentheses square root of fraction numerator straight x over denominator straight a plus straight x end fraction end root close parentheses dx
    Put square root of fraction numerator straight x over denominator straight a plus straight x end fraction end root space equals space sin space straight theta space space space or space space fraction numerator straight x over denominator straight a plus straight x end fraction space equals space sin squared straight theta
    therefore space space space space straight x space space equals straight a space sin squared space straight theta space plus space straight x space sin squared space straight theta space space space space space space rightwards double arrow space space space space space straight x left parenthesis 1 minus sin squared straight theta right parenthesis space equals space straight a space sin squared straight theta
    rightwards double arrow space space space space straight x space cos squared straight theta space equals space straight a space sin squared straight theta space space space space space space space rightwards double arrow space space space straight x space equals space straight a space tan squared straight theta
    therefore space space space space space space space space space dx space equals space 2 space straight a space tanθ space space sec squared straight theta space dθ
    When x = 0,  sin space straight theta space equals space 0      rightwards double arrow space space space straight theta space equals space 0
    When x = a,  sin space straight theta space equals space square root of fraction numerator straight a over denominator straight a plus straight a end fraction end root space equals space fraction numerator 1 over denominator square root of 2 end fraction space space space space rightwards double arrow space space space space straight theta space equals space straight pi over 4
       thereforestraight I space equals space integral subscript 0 superscript straight pi over 4 end superscript space sin to the power of negative 1 end exponent left parenthesis sin space straight theta right parenthesis. space 2 space straight a space tanθ space sec squared straight theta space dθ space equals space 2 straight a integral subscript 0 superscript straight pi over 4 end superscript space straight theta. space left parenthesis tanθ space sec squared straight theta right parenthesis space dθ
                  equals space 2 space straight a open curly brackets open square brackets straight theta. space fraction numerator tan squared straight theta over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 4 end superscript space minus space integral subscript 0 superscript straight pi over 4 end superscript 1. space fraction numerator tan squared space straight theta over denominator 2 end fraction dθ close curly brackets
                  equals space straight a space open square brackets straight theta space tan squared straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript space minus space straight a integral subscript 0 superscript straight pi over 4 end superscript space left parenthesis sec squared straight theta minus 1 right parenthesis space dθ
equals space straight a open square brackets straight theta space tan squared straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript space minus space straight a space open square brackets tanθ space minus space straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript
equals space straight a open square brackets straight pi over 4 cross times tan squared straight pi over 4 minus 0 close square brackets space minus space straight a open square brackets open parentheses tan straight pi over 4 minus straight pi over 4 close parentheses minus left parenthesis tan space 0 space minus 0 right parenthesis close square brackets
equals space straight a cross times straight pi over 4 cross times 1 minus straight a open parentheses 1 minus straight pi over 4 close parentheses
space equals space πa over 4 minus straight a plus πa over 4 space equals space fraction numerator straight pi space straight a over denominator 2 end fraction minus straight a space equals space straight a open parentheses straight pi over 2 minus 1 close parentheses space equals space fraction numerator straight a left parenthesis straight pi minus 2 right parenthesis over denominator 2 end fraction

    Question 113
    CBSEENMA12032507

    Evaluate: 
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 4 cosx plus 2 sinx end fraction.

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 4 space cosx plus 2 sinx end fraction dx
    Put tan straight x over 2 space equals space straight t comma space space space space space therefore space space space straight x over 2 space equals space tan to the power of negative 1 end exponent space straight t space space rightwards double arrow space space space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space space space space rightwards double arrow space space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    When x = 0,  straight t equals space tan 0 space equals space 0
    When straight x equals space straight pi over 2 comma space space space space space space straight t space equals space tan straight pi over 4 equals 1
    Also     sinx space equals space fraction numerator 2 tan begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction. space cos space straight x space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
              straight I space equals space integral subscript 0 superscript 1 fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 4 open parentheses begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style close parentheses plus 2 open parentheses begin display style fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction end style close parentheses end fraction space equals integral subscript 0 superscript 1 fraction numerator 1 over denominator 2 space left parenthesis 1 minus straight t squared right parenthesis space plus space 2 straight t end fraction dt
              equals 1 half integral subscript 0 superscript 1 fraction numerator 1 over denominator 1 plus straight t minus straight t squared end fraction space equals space 1 half integral fraction numerator 1 over denominator 1 minus left parenthesis straight t squared minus straight t right parenthesis end fraction dt space equals space 1 half integral fraction numerator 1 over denominator begin display style 5 over 4 end style minus open parentheses straight t squared minus straight t plus begin display style 1 fourth end style close parentheses end fraction dt
             equals space 1 half integral fraction numerator 1 over denominator open parentheses begin display style fraction numerator square root of 5 over denominator 2 end fraction end style close parentheses squared minus open parentheses straight t minus begin display style 1 over straight t end style close parentheses squared end fraction dt space equals space 1 half space equals space fraction numerator 1 over denominator 2 begin display style fraction numerator square root of 5 over denominator 2 end fraction end style end fraction open square brackets log open vertical bar fraction numerator begin display style fraction numerator square root of 5 over denominator 2 end fraction end style plus open parentheses straight t minus begin display style 1 half end style close parentheses over denominator begin display style fraction numerator square root of 5 over denominator 2 end fraction end style minus open parentheses straight t minus begin display style 1 half end style close parentheses end fraction close vertical bar close square brackets subscript 0 superscript 1
    equals fraction numerator 1 over denominator 2 square root of 5 end fraction open square brackets log space open parentheses fraction numerator square root of 5 plus 1 over denominator square root of 5 minus 1 end fraction close parentheses minus log open parentheses fraction numerator square root of 5 minus 1 over denominator square root of 5 plus 1 end fraction close parentheses close square brackets
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator square root of 5 plus 1 over denominator square root of 5 minus 1 end fraction cross times fraction numerator square root of 5 plus 1 over denominator square root of 5 minus 1 end fraction close parentheses space equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 5 plus 1 plus 2 square root of 5 over denominator 5 plus 1 minus 2 square root of 5 end fraction close parentheses
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 3 minus square root of 5 end fraction close parentheses space equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 3 minus square root of 5 end fraction cross times fraction numerator 3 plus square root of 5 over denominator 3 plus square root of 5 end fraction close parentheses
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open square brackets fraction numerator left parenthesis 3 plus square root of 5 right parenthesis squared over denominator 4 end fraction close square brackets space equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 2 end fraction close parentheses squared space equals space fraction numerator 1 over denominator square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 2 end fraction close parentheses
              
             

    Question 114
    CBSEENMA12032509

    Evaluate
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 2 space cosx space plus space 4 space sinx end fraction

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript space fraction numerator dx over denominator 2 space cosx space plus space 4 sinx end fraction
    Put tan space straight x over 2 space equals space straight t comma space space space therefore space space straight x over 2 space equals space tan to the power of negative 1 end exponent straight t space space space rightwards double arrow space space space space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space space rightwards double arrow space space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    When x  = 0   t = tan 0  = 0
    When straight x equals space straight pi over 2 comma space space space straight t equals space tan straight pi over 4 space equals space 1
    Also sinx space equals space fraction numerator 2 space tan begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction comma space space cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
    therefore           straight I space equals space integral subscript 0 superscript 1 fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 2 open parentheses begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style close parentheses plus 4 open parentheses begin display style fraction numerator 2 straight t over denominator 1 minus straight t squared end fraction end style close parentheses end fraction space equals space integral subscript 0 superscript 1 fraction numerator dt over denominator 1 minus straight t squared plus 4 straight t end fraction
                       equals integral subscript 0 superscript 1 fraction numerator 1 over denominator 1 minus left parenthesis straight t squared minus 4 straight t right parenthesis end fraction dt space equals space integral subscript 0 superscript 1 fraction numerator dt over denominator left parenthesis 1 plus 4 right parenthesis space minus left parenthesis straight t squared minus 4 straight t plus 4 right parenthesis end fraction space equals integral subscript 0 superscript 1 fraction numerator dt over denominator left parenthesis square root of 5 right parenthesis squared minus left parenthesis straight t minus 2 right parenthesis squared end fraction
                     equals space fraction numerator 1 over denominator 2 square root of 5 end fraction open square brackets log space open vertical bar fraction numerator square root of 5 plus left parenthesis straight t minus 2 right parenthesis over denominator square root of 5 minus left parenthesis straight t minus 2 right parenthesis end fraction close vertical bar close square brackets subscript 0 superscript 1 space equals space fraction numerator 1 over denominator 2 square root of 5 end fraction open square brackets log space fraction numerator square root of 5 minus 1 over denominator square root of 5 plus 1 end fraction minus log open parentheses fraction numerator square root of 5 minus 2 over denominator square root of 5 plus 2 end fraction close parentheses close square brackets
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator square root of 5 minus 1 over denominator square root of 5 minus 1 end fraction cross times fraction numerator square root of 5 plus 2 over denominator square root of 5 minus 2 end fraction close parentheses
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log space open parentheses fraction numerator 5 minus 2 plus square root of 5 over denominator 5 minus 2 minus square root of 5 end fraction close parentheses space equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 3 minus square root of 5 end fraction close parentheses
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 3 minus square root of 5 end fraction cross times fraction numerator 3 plus square root of 5 over denominator 3 plus square root of 5 end fraction close parentheses space equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open square brackets fraction numerator left parenthesis 3 plus square root of 5 right parenthesis squared over denominator 4 end fraction close square brackets
equals space fraction numerator 1 over denominator 2 square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 2 end fraction close parentheses squared space equals space fraction numerator 1 over denominator square root of 5 end fraction log open parentheses fraction numerator 3 plus square root of 5 over denominator 2 end fraction close parentheses

    Question 115
    CBSEENMA12032511

    Evaluate
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator sinx plus square root of 3 cosx end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator sinx plus square root of 3 cosx end fraction dx
    Put   1 space equals straight r space cos space straight alpha                                          ...(1)
    and   square root of 3 space equals space straight r space sin space straight alpha                                      ...(2)
    Squaring and adding (1) and (2), we get
                           4 space equals space straight r squared                       rightwards double arrow space space space straight r space equals space 2
    Dividing (2) by (1), tan space straight alpha space equals space square root of 3             rightwards double arrow space space space straight a space equals space straight pi over 3
    therefore       straight I space equals space 1 over straight r integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator sinx space cosα space plus space cosx space sinα end fraction dx space equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator sin left parenthesis straight x plus straight alpha right parenthesis end fraction dx
                  equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript cosec left parenthesis straight x plus straight alpha right parenthesis space dx space equals space 1 half open square brackets negative log space open vertical bar cosec left parenthesis straight x plus straight alpha right parenthesis plus cot left parenthesis straight x plus straight a right parenthesis close vertical bar close square brackets subscript 0 superscript straight pi over 2 end superscript
                 equals space minus 1 half open square brackets log space open vertical bar cosec space open parentheses straight pi over 2 plus straight pi over 3 close parentheses plus cot space open parentheses straight pi over 2 plus straight pi over 3 close parentheses close vertical bar minus log open vertical bar cosec straight pi over 3 plus cot straight pi over 3 close vertical bar close square brackets
         equals negative 1 half open square brackets log space open vertical bar sec straight pi over 3 minus tan straight pi over 3 close vertical bar minus log open vertical bar cosec straight pi over 3 plus cot straight pi over 3 close vertical bar close square brackets
          equals negative 1 half open square brackets log space open vertical bar 2 minus square root of 3 close vertical bar minus log space open vertical bar fraction numerator 2 over denominator square root of 3 end fraction plus fraction numerator 1 over denominator square root of 3 end fraction close vertical bar close square brackets
equals negative 1 half open square brackets log left parenthesis 2 minus square root of 3 right parenthesis space minus space log square root of 3 close square brackets
equals space minus 1 half log open parentheses fraction numerator 2 minus square root of 3 over denominator square root of 3 end fraction close parentheses

    Question 116
    CBSEENMA12032513

    Prove that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 9 plus 16 space cos squared straight x end fraction space equals space straight pi over 30

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 9 plus 16 space cos squared straight x end fraction space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 9 space left parenthesis sin squared straight x plus cos squared straight x right parenthesis plus 16 cos squared straight x end fraction
           equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 9 space sin squared straight x plus 25 space cos squared straight x end fraction space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator begin display style fraction numerator 1 over denominator cos squared space straight x end fraction end style dx over denominator begin display style fraction numerator 9 space sin squared straight x over denominator cos squared straight x end fraction end style plus begin display style fraction numerator 25 space cos squared straight x over denominator cos squared straight x end fraction end style end fraction
          equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sec squared xdx over denominator 9 space tan squared straight x plus 25 end fraction
    Put  tan x = t,    ∴ sec2 x dx = dt
    When x = 0, t = tan 0 = 0
    When   straight x space equals space straight pi over 2 comma space space straight t space equals space tan straight pi over 2 space equals space infinity
    therefore        straight I space equals space integral subscript 0 superscript infinity fraction numerator dt over denominator 9 straight t squared plus 25 end fraction space equals space 1 over 9 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus begin display style 25 over 9 end style end fraction dt space equals space 1 over 9 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus open parentheses begin display style 5 over 3 end style close parentheses squared end fraction dt
                   equals space 1 over 9. fraction numerator 1 over denominator begin display style 5 over 3 end style end fraction open square brackets tan to the power of negative 1 end exponent fraction numerator straight t over denominator open parentheses begin display style 5 over 3 end style close parentheses end fraction close square brackets subscript 0 superscript infinity space equals 1 over 15 open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator 3 straight t over denominator 5 end fraction close parentheses close square brackets subscript 0 superscript infinity
                     equals space 1 over 15 open square brackets tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 close square brackets space equals space 1 over 15 open square brackets straight pi over 2 minus 0 close square brackets space equals space straight pi over 30

    Question 117
    CBSEENMA12032514

    Prove that:
    integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sin space 2 straight theta space dθ over denominator sin to the power of 4 space straight theta space plus space cos to the power of 4 straight theta end fraction space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sin space 2 straight theta over denominator sin to the power of 4 straight theta space plus space cos to the power of 4 straight theta end fraction dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 2 space sin space straight theta space cos space straight theta space dθ over denominator sin to the power of 4 straight theta space plus space cos to the power of 4 straight theta end fraction
             equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator begin display style fraction numerator 2 space sin space straight theta space cosθ over denominator cos to the power of 4 straight theta end fraction end style over denominator begin display style fraction numerator sin to the power of 4 straight theta over denominator cos to the power of 4 straight theta end fraction end style plus begin display style fraction numerator cos to the power of 4 straight theta over denominator cos to the power of 4 straight theta end fraction end style end fraction dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 2 space tanθ space sec squared straight theta over denominator tan to the power of 4 straight theta plus 1 end fraction dθ
    Put tan2 θ = t,    ∴ 2 tan θ sec2 θ dθ = dt      When θ = 0, t = tan2 0 = 0
    When straight theta space equals space straight pi over 4 comma space space space straight t space space equals tan squared straight pi over 4 space equals space 1
    therefore       straight I space equals space integral subscript 0 superscript 1 fraction numerator dt over denominator straight t squared plus 1 end fraction space equals space left square bracket tan to the power of negative 1 end exponent straight t right square bracket subscript 0 superscript 1 space equals space tan to the power of negative 1 end exponent 1 space minus space tan to the power of negative 1 end exponent 0 space equals space straight pi over 4 minus 0 space equals space straight pi over 4

    Question 118
    CBSEENMA12032516

    Prove that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space 2 straight ϕ space dϕ over denominator sin to the power of 4 straight ϕ plus cos to the power of 4 straight ϕ end fraction space equals space straight pi over 2

    Solution

    Let I  = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space 2 straight ϕ over denominator sin to the power of 4 straight ϕ plus cos to the power of 4 straight ϕ end fraction dϕ space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 2 sinϕcosϕ over denominator sin to the power of 4 straight ϕ plus cos to the power of 4 straight ϕ end fraction dϕ
             equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator begin display style fraction numerator 2 space sin space straight ϕ space cosϕ over denominator cos to the power of 4 straight ϕ end fraction end style over denominator begin display style fraction numerator sin to the power of 4 straight ϕ over denominator cos to the power of 4 straight ϕ end fraction end style plus begin display style fraction numerator cos to the power of 4 straight ϕ over denominator cos to the power of 4 straight ϕ end fraction end style end fraction dϕ space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 2 space tanϕ space sec squared space straight ϕ space dϕ over denominator tan to the power of 4 straight ϕ plus 1 end fraction
    Put tan2 ϕ = y ,    ∴ 2 tan ϕ sec2 ϕ dϕ = dy   When ϕ = 0, y = tan2 0 = 0
    When straight ϕ space equals space straight pi over 2 comma space space straight y space equals tan squared straight pi over 2 space rightwards arrow space space infinity
    therefore space space space space space straight I space equals space integral subscript 0 superscript infinity fraction numerator dy over denominator straight y squared plus 1 end fraction space equals space open square brackets tan to the power of negative 1 end exponent space straight y close square brackets subscript 0 superscript infinity space equals space tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 space equals space straight pi over 2 minus 0 space equals space straight pi over 2

    Question 119
    CBSEENMA12032517

    Prove that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cosx space dx over denominator left parenthesis 1 plus sin space straight x right parenthesis space left parenthesis 2 plus sinx right parenthesis end fraction space equals space log space 4 over 3


    Solution

    Let
    straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cosx space dx over denominator left parenthesis 1 plus sinx right parenthesis space left parenthesis 2 plus sinx right parenthesis end fraction
    Put sin x = t,                 ∴ cos x dx = dt 
    When x = 0, t = sin 0 = 0
    When    straight x space equals space straight pi over 2 comma space space space straight t space equals space sin straight pi over 2 space equals space 1
                  I = integral subscript 0 superscript 1 fraction numerator dt over denominator left parenthesis 1 plus straight t right parenthesis space left parenthesis 2 plus straight t right parenthesis end fraction    [Do not forget to change limits of integration]
                     equals space integral subscript 0 superscript 1 open square brackets fraction numerator 1 over denominator left parenthesis 1 plus straight t right parenthesis space left parenthesis 2 minus 1 right parenthesis end fraction plus fraction numerator 1 over denominator left parenthesis 1 minus 2 right parenthesis thin space left parenthesis 2 plus straight t right parenthesis end fraction close square brackets dt
                     equals space integral subscript 0 superscript 1 open square brackets fraction numerator 1 over denominator 1 plus straight t end fraction minus fraction numerator 1 over denominator 2 plus straight t end fraction close square brackets dt space equals space open square brackets log space left parenthesis 1 plus straight t right parenthesis space minus space log left parenthesis 2 plus straight t right parenthesis close square brackets subscript 0 superscript 1
                      equals space open square brackets log space fraction numerator 1 plus straight t over denominator 2 plus straight t end fraction close square brackets subscript 0 superscript 1 space equals space log 2 over 3 minus log 1 half space equals space log open parentheses fraction numerator begin display style 2 over 3 end style over denominator begin display style 1 half end style end fraction close parentheses space equals space log 4 over 3

    Sponsor Area

    Question 120
    CBSEENMA12032522

    Evaluate: integral subscript 0 superscript straight pi over 4 end superscript space fraction numerator sinx space cosx over denominator cos squared straight x plus sin to the power of 4 straight x end fraction dx.

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sinx space cosx over denominator cos squared straight x plus sin to the power of 4 straight x end fraction dx space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 4 space sinx space cosx over denominator 2 space left parenthesis 2 space cos squared straight x right parenthesis space plus space left parenthesis 2 space sin squared straight x right parenthesis squared end fraction dx
          equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 2 space sin 2 straight x over denominator 2 left parenthesis 1 plus cos 2 straight x right parenthesis plus left parenthesis 1 minus cos 2 straight x right parenthesis squared end fraction dx space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator 2 space sin 2 straight x over denominator 3 plus cos squared straight x end fraction dx
    Put cos 2x =y,    ∴ –2 sin 2x dx = dy ⇒ 2 sin 2x dx = dy
    When x = 0, y = cos 0 = 1
    When straight x space equals space straight pi over 4 comma space space space straight y space equals space cos straight pi over 2 space equals space 0
    therefore       I = -integral subscript 1 superscript 0 fraction numerator 1 over denominator 3 plus straight y squared end fraction dy space equals space minus integral subscript 1 superscript 0 fraction numerator 1 over denominator straight y squared plus left parenthesis square root of 3 right parenthesis squared end fraction dy space equals space minus fraction numerator 1 over denominator square root of 3 end fraction open square brackets tan to the power of negative 1 end exponent fraction numerator straight y over denominator square root of 3 end fraction close square brackets subscript 1 superscript 0
                 equals negative fraction numerator 1 over denominator square root of 3 end fraction open square brackets tan to the power of negative 1 end exponent 0 space minus tan to the power of negative 1 end exponent fraction numerator 1 over denominator square root of 3 end fraction close square brackets space equals space minus fraction numerator 1 over denominator square root of 3 end fraction open square brackets 0 minus straight pi over 6 close square brackets space equals space fraction numerator straight pi over denominator 6 square root of 3 end fraction

    Question 121
    CBSEENMA12032524

    Evaluate the following definite integral:
    integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sinx space cosx over denominator cos to the power of 4 straight x space plus space sin to the power of 4 straight x end fraction dx

    Solution

    Let
    I = integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sinx space cosx over denominator cos to the power of 4 straight x plus sin to the power of 4 straight x end fraction dx space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator begin display style fraction numerator sinx space cosx over denominator cos to the power of 4 straight x end fraction end style over denominator begin display style fraction numerator cos to the power of 4 straight x over denominator cos to the power of 4 straight x end fraction end style plus begin display style fraction numerator sin to the power of 4 straight x over denominator cos to the power of 4 straight x end fraction end style end fraction dx
    equals integral subscript 0 superscript straight pi over 4 end superscript fraction numerator begin display style sinx over cosx end style minus begin display style fraction numerator 1 over denominator cos squared straight x end fraction end style over denominator 1 plus begin display style fraction numerator sin to the power of 4 straight x over denominator cos to the power of 4 straight x end fraction end style end fraction dx space equals integral subscript 0 superscript straight pi over 4 end superscript fraction numerator tan space straight x space sec squared straight x over denominator 1 plus tan to the power of 4 straight x end fraction dx
    Put tan 2 x = y, ∴ 2 tan x sec2 x dx = dy

    thereforeWhen x = 0, y = tan2 0 = 0
    When straight x equals space straight pi over 4 comma space space space straight y space equals space tan squared straight pi over 4 equals space 1
    therefore space space space space straight I space equals space 1 half integral subscript 0 superscript 1 fraction numerator 1 over denominator 1 plus straight y squared end fraction dy space equals space 1 half open square brackets tan to the power of negative 1 end exponent straight y close square brackets subscript 0 superscript 1 space equals space 1 half open square brackets tan to the power of negative 1 end exponent 1 minus tan to the power of negative 1 end exponent 0 close square brackets space equals space 1 half open parentheses straight pi over 4 minus 0 close parentheses space equals space straight pi over 8

    Question 122
    CBSEENMA12032528

    Evaluate the following definite integral:
    integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator sinx plus cosx over denominator square root of sin space 2 straight x end root end fraction dx.

    Solution

    Let 
    straight I space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator sinx plus cosx over denominator square root of sin space 2 straight x end root end fraction dx space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator sinx plus cosx over denominator square root of 1 minus left parenthesis 1 minus sin space 2 straight x right parenthesis end root end fraction dx
       equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator sinx plus cosx over denominator square root of 1 minus left parenthesis 1 minus sin space 2 straight x right parenthesis end root end fraction dx space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator sinx plus cosx over denominator square root of 1 minus left parenthesis sinx minus cosx right parenthesis squared end root end fraction dx
    Put sin x – cos x = y,     ∴    (cos x + sin x) dx = dy
    When   straight x space equals space straight pi over 6 comma space space straight y space equals space sin straight pi over 6 minus cos straight pi over 6 space equals space 1 half minus fraction numerator square root of 3 over denominator 2 end fraction
    When   straight x space equals space straight pi over 3 comma space space space straight y space equals space sin straight pi over 3 minus cos straight pi over 3 space equals space fraction numerator square root of 3 over denominator 2 end fraction minus 1 half
    therefore space space space space space space space space space space space space space space space space space space space straight I space space equals space integral subscript fraction numerator 1 over denominator square root of 2 end fraction minus fraction numerator square root of 3 over denominator 2 end fraction end subscript superscript fraction numerator square root of 3 over denominator 2 end fraction minus 1 half end superscript space space fraction numerator 1 over denominator square root of 1 minus straight t squared end root end fraction dt space equals space open square brackets sin to the power of negative 1 end exponent straight t close square brackets subscript 1 half minus fraction numerator square root of 3 over denominator 2 end fraction end subscript superscript fraction numerator square root of 3 over denominator 2 end fraction minus 1 half end superscript
                            sin to the power of negative 1 end exponent open parentheses fraction numerator square root of 3 over denominator 2 end fraction minus 1 half close parentheses space minus space sin to the power of negative 1 end exponent open parentheses 1 half minus fraction numerator square root of 3 over denominator 2 end fraction close parentheses
                         equals space sin to the power of negative 1 end exponent open parentheses fraction numerator square root of 3 over denominator 2 end fraction minus 1 half close parentheses space plus space sin to the power of negative 1 end exponent open parentheses fraction numerator square root of 3 over denominator 2 end fraction minus 1 half close parentheses space equals space 2 sin to the power of negative 1 end exponent open parentheses fraction numerator square root of 3 minus 1 over denominator 2 end fraction close parentheses

    Question 123
    CBSEENMA12032530

    Evaluate the following definite integral:
    integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sinx plus cosx over denominator 9 plus 16 sin 2 straight x end fraction dx

    Solution

    Let I =integral subscript 0 superscript straight pi over 4 end superscript fraction numerator sinx plus cosx over denominator 9 plus 16 sin 2 straight x end fraction dx
    Put sin x – cos x = t,        ∴ (cos x + sin x) dx = dt
    Also sin2 x + cos2 x – 2 sin x cos x = t2 ⇒ 1 – sin 2 x = t2 When x = 0, t = sin 0 – cos 0 = 0 – 1= – 1

    When straight x equals space straight pi over 4 comma space space space straight t space equals space sin straight pi over 4 minus cos straight pi over 4 space equals space fraction numerator 1 over denominator square root of 2 end fraction minus fraction numerator 1 over denominator square root of 2 end fraction equals 0
            straight I space equals space integral subscript negative 1 end subscript superscript 0 fraction numerator 1 over denominator 9 plus 16 left parenthesis 1 minus straight t squared right parenthesis end fraction dt space equals space integral subscript negative 1 end subscript superscript 0 fraction numerator 1 over denominator 25 minus 16 straight t squared end fraction dt
              equals space 1 over 16 integral subscript negative 1 end subscript superscript 0 space fraction numerator 1 over denominator open parentheses begin display style 5 over 4 end style close parentheses squared minus straight t squared end fraction space dt space equals space 1 over 16 cross times fraction numerator 1 over denominator 2 cross times begin display style 5 over 4 end style end fraction open square brackets log space open vertical bar fraction numerator begin display style 5 over 4 end style plus straight t over denominator begin display style 5 over 4 end style minus straight t end fraction close vertical bar close square brackets subscript negative 1 end subscript superscript 0
equals space 1 over 40 open parentheses log space 1 space minus space log space 1 over 9 close parentheses space equals space 1 over 40 left parenthesis log space 1 space minus space log space 1 space plus space log space 9 right parenthesis
space equals space 1 over 40 space log space 9. 
    Question 124
    CBSEENMA12032534

    Evaluate the following definite integral:
    integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x space tan to the power of negative 1 end exponent left parenthesis sin space straight x right parenthesis space dx.


    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript sin space 2 space straight x space tan to the power of negative 1 end exponent space left parenthesis sin space straight x right parenthesis space dx space equals space integral subscript 0 superscript straight pi over 2 end superscript space 2 sinx space cosx. space tan to the power of negative 1 end exponent left parenthesis sinx right parenthesis space dx
    Put sin x = t,    ∴ cos x dx = dt
    When x = 0. t = sin 0 = 0
    When    straight x space equals space straight pi over 2. space space space space space straight t space equals space sin straight pi over 2 space equals space 1
    therefore                 straight I space equals space 2 integral subscript 0 superscript 1 straight t. space tan to the power of negative 1 end exponent straight t space dt space equals space 2 integral subscript 0 superscript 1 left parenthesis tan to the power of negative 1 end exponent straight t right parenthesis space straight t space dt
                            equals 2 open square brackets tan to the power of negative 1 end exponent straight t. straight t squared over 2 close square brackets subscript 0 superscript 1 space minus space 2 integral subscript 0 superscript 1 fraction numerator 1 over denominator 1 plus straight t squared end fraction. straight t squared over 2 dt
                            equals space open square brackets straight t squared space tan to the power of negative 1 end exponent space straight t close square brackets subscript 0 superscript 1 space minus space integral subscript 0 superscript 1 space fraction numerator straight t squared over denominator 1 plus straight t squared end fraction dt space space equals space left parenthesis tan to the power of negative 1 end exponent 1 minus 0 right parenthesis minus integral subscript 0 superscript 1 open parentheses 1 minus fraction numerator 1 over denominator 1 plus straight t squared end fraction close parentheses dt
                            equals space straight pi over 4 minus open square brackets straight t minus tan to the power of negative 1 end exponent straight t close square brackets subscript 0 superscript 1 space equals space straight pi over 4 minus left square bracket left parenthesis 1 minus tan to the power of negative 1 end exponent right parenthesis space minus space left parenthesis 0 minus tan to the power of negative 1 end exponent 0 right parenthesis right square bracket
equals space straight pi over 4 minus open square brackets open parentheses 1 minus straight pi over 4 close parentheses minus left parenthesis 0 minus 0 right parenthesis close square brackets space equals space straight pi over 2 minus 1

    Question 125
    CBSEENMA12032535

    Prove that integral subscript 0 superscript straight pi fraction numerator dx over denominator 5 plus 3 cosx end fraction space equals space straight pi over 4

    Solution

    Let 
        I = integral subscript 0 superscript straight pi fraction numerator dx over denominator 5 plus 3 space cosx end fraction
    Put tan straight x over 2 space equals space straight t   or   straight x over 2 space equals space tan to the power of negative 1 end exponent straight t   or   straight x equals 2 tan to the power of negative 1 end exponent straight t space space space space space space rightwards double arrow space space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    Also         cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
    When         straight x space equals space 0 comma space space space space space space space space straight t space equals space tan space 0 space equals space 0
    When         straight x equals space straight pi comma space space space space space straight t space equals space tan straight pi over 2 space equals space infinity
    therefore    I = integral subscript 0 superscript infinity fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 5 plus 3 open parentheses begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style close parentheses end fraction space equals space integral subscript 0 superscript infinity fraction numerator 2 over denominator 5 space left parenthesis 1 plus straight t squared right parenthesis plus 3 space left parenthesis 1 minus straight t squared right parenthesis end fraction dt
              equals space integral subscript 0 superscript infinity fraction numerator 2 over denominator 2 straight t squared plus 8 end fraction dt space equals space integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus 4 end fraction dt space equals space integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus left parenthesis 2 right parenthesis squared end fraction dt
equals space 1 half. space space space open square brackets tan to the power of negative 1 end exponent straight t over 2 close square brackets subscript 0 superscript infinity space equals space 1 half left parenthesis tan to the power of negative 1 end exponent infinity space minus tan to the power of negative 1 end exponent 0 right parenthesis space equals space 1 half open parentheses straight pi over 2 minus 0 close parentheses space equals straight pi over 4.

    Question 126
    CBSEENMA12032536

    Evaluate integral subscript 0 superscript straight pi fraction numerator dx over denominator 5 plus 4 space cosx end fraction.

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator dx over denominator 5 plus 4 space cosx end fraction
    Put   tan space straight x over 2 space equals space straight t space space space space or space space space space straight x over 2 space equals space tan to the power of negative 1 end exponent straight t space space space space space space or space space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space space space space space rightwards double arrow space space space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
                      cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
    When x = 0, t = tan 0 = 0
    When straight x equals space straight pi over 2 comma space space straight t space equals space tan straight pi over 2 space equals space infinity
    therefore      I = integral subscript 0 superscript infinity fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 5 plus 4 open parentheses begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style close parentheses end fraction space equals space integral subscript 0 superscript infinity fraction numerator 2 space dt over denominator 5 space left parenthesis 1 plus straight t squared right parenthesis space plus space 4 left parenthesis 1 minus straight t squared right parenthesis end fraction
             equals space 2 integral subscript 0 superscript infinity fraction numerator dt over denominator straight t squared plus 9 end fraction space equals space 2 integral subscript 0 superscript infinity fraction numerator dt over denominator straight t squared plus left parenthesis 3 right parenthesis squared end fraction
equals 2. space 1 third open square brackets tan to the power of negative 1 end exponent straight t over 3 close square brackets subscript 0 superscript infinity space equals space 2 over 3 open square brackets tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 close square brackets space equals space 2 over 3 open square brackets straight pi over 2 minus 0 close square brackets space equals space straight pi over 3
                 

    Question 127
    CBSEENMA12032537

    Evaluate the following:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 5 plus 4 space sinx end fraction

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 5 plus 4 space sinx end fraction
    Put  tan space straight x over 2 space equals space straight t space space space space space space space space or space space space straight x over 2 space equals space tan to the power of negative 1 end exponent straight t comma space space space space space therefore space space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space space space space space space space space space space space rightwards double arrow space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction
                        sinx space equals space fraction numerator 2 tan begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction
    When x = 0,    t = tan 0 = 0
    When straight x space equals space straight pi over 2 comma space space straight t space equals space tan straight pi over 4 space equals space 1
    therefore     straight I space equals space integral subscript 0 superscript 1 fraction numerator begin display style fraction numerator 2 space dt over denominator 1 plus straight t squared end fraction end style over denominator 5 plus 4 open parentheses begin display style fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction end style close parentheses end fraction space equals space integral subscript 0 superscript 1 fraction numerator 2 space dt over denominator 5 plus 5 straight t squared plus 8 straight t end fraction space equals space 2 over 5 integral subscript 0 superscript 1 fraction numerator dt over denominator straight t squared plus begin display style 8 over 5 end style straight t plus 1 end fraction 2 over 5           equals space integral subscript 0 superscript 1 fraction numerator dt over denominator open parentheses straight r squared plus begin display style 8 over 5 end style straight t plus begin display style 16 over 25 end style close parentheses plus begin display style 9 over 25 end style end fraction space equals space 2 over 5 integral subscript 0 superscript 1 fraction numerator dt over denominator open parentheses straight t plus begin display style 4 over 5 end style close parentheses squared plus open parentheses begin display style 3 over 5 end style close parentheses squared end fraction space equals 2 over 5. fraction numerator 1 over denominator begin display style 3 over 5 end style end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight t plus begin display style 4 over 5 end style over denominator begin display style 3 over 5 end style end fraction close parentheses close square brackets subscript 0 superscript 1
     equals space 2 over 3 open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator 5 straight t plus 4 over denominator 3 end fraction close parentheses close square brackets subscript 0 superscript 1 space equals space 2 over 3 open square brackets tan to the power of negative 1 end exponent space 3 space minus space tan to the power of negative 1 end exponent 4 over 3 close square brackets
space equals space 2 over 3 tan to the power of negative 1 end exponent open square brackets fraction numerator 3 minus begin display style 4 over 3 end style over denominator 1 plus 3 cross times begin display style 4 over 3 end style end fraction close square brackets space space space space space space space space space space space space space space open square brackets because space space tan to the power of negative 1 end exponent straight a minus tan to the power of negative 1 end exponent straight b space equals space tan to the power of negative 1 end exponent open parentheses fraction numerator straight a minus straight b over denominator 1 plus straight a space straight b end fraction close parentheses close square brackets
equals space 2 over 3 tan to the power of negative 1 end exponent open parentheses fraction numerator begin display style 5 over 3 end style over denominator 5 end fraction close parentheses space equals space 2 over 3 tan to the power of negative 1 end exponent open parentheses 1 third close parentheses

    Question 128
    CBSEENMA12032538

    Evaluate the following:
    integral subscript 0 superscript straight pi fraction numerator 1 over denominator 5 plus 2 cosx end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator 1 over denominator 5 plus 2 cosx end fraction dx
    Put  tan straight x over 2 space equals space straight t comma space space space or space space straight x over 2 space equals space tan to the power of negative 1 end exponent straight t comma space space space or space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space rightwards double arrow space space space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    When x = 0, t = tan 0 = 0
    When straight x equals straight pi comma space space straight t space equals tan straight pi over 2 rightwards arrow infinity
    Also  cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
    therefore       straight I space equals space integral subscript 0 superscript infinity fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 5 plus 2 open parentheses begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style close parentheses end fraction space equals space integral subscript 0 superscript infinity fraction numerator 2 over denominator 5 space left parenthesis 1 plus straight t squared right parenthesis space plus 2 space left parenthesis 1 minus straight t squared right parenthesis end fraction dt
                  equals space 2 space integral subscript 0 superscript infinity fraction numerator 1 over denominator 3 straight t squared plus 7 end fraction dt space equals space 2 over 3 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus begin display style 7 over 3 end style end fraction dt space equals space 2 over 3 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus open parentheses begin display style fraction numerator square root of 7 over denominator 3 end fraction end style close parentheses squared end fraction dt
                  equals space 2 over 3 fraction numerator 1 over denominator square root of begin display style 7 over 3 end style end root end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight t over denominator square root of begin display style 7 over 3 end style end root end fraction close parentheses close square brackets subscript 0 superscript infinity space equals space fraction numerator 2 over denominator square root of 21 end fraction left square bracket tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 right square bracket
space equals fraction numerator 2 over denominator square root of 21 end fraction open square brackets straight pi over 2 minus 0 close square brackets space equals space fraction numerator straight pi over denominator square root of 21 end fraction

    Question 129
    CBSEENMA12032539

    Evaluate the following:
    integral subscript 0 superscript straight pi fraction numerator 1 over denominator 6 minus cosx end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator 1 over denominator 6 minus cosx end fraction dx
    Put tan space straight x over 2 space equals space straight t comma space space space or space space straight x over 2 space equals space tan to the power of negative 1 end exponent straight t comma space space space or space space straight x space equals space 2 space tan to the power of negative 1 end exponent space straight t space space rightwards double arrow space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    When x = 0. t = tan 0 = 0
    When straight x space equals space straight pi comma space space space straight t space equals space tan straight pi over 2 space rightwards arrow space infinity
    Also  cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
     therefore           straight I space equals space integral subscript 0 superscript infinity fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 6 minus begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style end fraction space equals integral subscript 0 superscript infinity fraction numerator 2 over denominator 6 plus 6 straight t squared minus 1 plus straight t squared end fraction dt space equals space 2 integral subscript 0 superscript infinity fraction numerator 1 over denominator 7 straight t squared plus 5 end fraction dt
                      equals space 2 over 7 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus open parentheses begin display style fraction numerator square root of 5 over denominator 7 end fraction end style close parentheses squared end fraction dt space equals space 2 over 7. fraction numerator 1 over denominator square root of begin display style 5 over 7 end style end root end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight t over denominator square root of begin display style 5 over 7 end style end root end fraction close parentheses close square brackets subscript 0 superscript infinity
equals space fraction numerator 2 over denominator square root of 35 end fraction left square bracket tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 right square bracket space equals space fraction numerator 2 over denominator square root of 35 end fraction open square brackets straight pi over 2 minus 0 close square brackets space equals space fraction numerator straight pi over denominator square root of 35 end fraction

    Question 130
    CBSEENMA12032540

    Evaluate the following:
    integral subscript 0 superscript straight pi fraction numerator dx over denominator 1 plus sin space straight x end fraction


    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator dx over denominator 1 plus sinx end fraction
    Put tan straight x over 2 space equals space straight t comma space space space or space space straight x over 2 equals space tan to the power of negative 1 end exponent straight t comma space space or space space straight x space equals space 2 tan to the power of negative 1 end exponent straight t space space rightwards double arrow space space space dx space space equals fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
         sinx space equals space fraction numerator 2 tan begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction
    When x = 0. t = tan 0 = 0
    When straight x space equals space straight pi comma space space space straight t space equals space tan straight pi over 2 space rightwards arrow space infinity
    therefore              straight I space equals space integral subscript 0 superscript infinity fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator 1 plus begin display style fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction end style end fraction space equals space integral subscript 0 superscript infinity fraction numerator 2 over denominator 1 plus straight t squared plus 2 straight t end fraction dt space equals space 2 integral subscript 0 superscript infinity fraction numerator dt over denominator left parenthesis straight t plus 1 right parenthesis squared end fraction space equals 2 integral subscript 0 superscript infinity left parenthesis straight t plus 1 right parenthesis to the power of negative 2 end exponent dt
                         equals space 2 open square brackets fraction numerator left parenthesis straight t plus 1 right parenthesis to the power of negative 1 end exponent over denominator negative 1 end fraction close square brackets subscript 0 superscript infinity space equals space minus 2 open square brackets fraction numerator 1 over denominator straight t plus 1 end fraction close square brackets subscript 0 superscript infinity space equals space minus 2 open square brackets Lt with straight t rightwards arrow infinity below fraction numerator 1 over denominator straight t plus 1 end fraction minus fraction numerator 1 over denominator 0 plus 1 end fraction close square brackets space equals space minus 2 left square bracket 0 minus 1 right square bracket space equals space 2

    Question 131
    CBSEENMA12032541

    Evaluate the following:
    integral subscript 0 superscript 1 sin to the power of negative 1 end exponent open parentheses fraction numerator 2 straight x over denominator 1 plus straight x squared end fraction close parentheses dx



    Solution

    Let I = integral subscript 0 superscript 1 space sin to the power of negative 1 end exponent space open parentheses fraction numerator 2 straight x over denominator 1 plus straight x squared end fraction close parentheses dx
    Put x = tan θ so that dx = sec2 θ dθ When x = 0, tan θ = 0 ⇒ θ = 0
    When x = 1,  tan space straight theta space equals space 1 space space space space space rightwards double arrow space space space straight theta space equals space straight pi over 4
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 4 end superscript space sin to the power of negative 1 end exponent space open parentheses fraction numerator 2 space tanθ over denominator 1 plus tan squared straight theta end fraction close parentheses. space sec squared straight theta space dθ
                equals space integral subscript 0 superscript straight pi over 4 end superscript space sin to the power of negative 1 end exponent left parenthesis sin space 2 straight theta right parenthesis. space sec squared straight theta space dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript 2 straight theta. space sec squared straight theta space dθ space equals space 2 integral subscript 0 superscript straight pi over 4 end superscript straight theta space. sec squared space straight theta space dθ
                equals space 2 open curly brackets open square brackets straight theta space tan space straight theta close square brackets subscript 1 superscript straight pi over 4 end superscript minus integral subscript 0 superscript straight pi over 4 end superscript 1. space tanθ space dθ close curly brackets space space equals space 2 open curly brackets open square brackets straight theta space tanθ close square brackets subscript 0 superscript straight pi over 4 end superscript plus open square brackets log space cosθ close square brackets subscript 0 superscript straight pi over 4 end superscript close curly brackets
equals space 2 open curly brackets straight pi over 4 tan straight pi over 4 minus 0 plus log space cos straight pi over 4 minus log space cos 0 close curly brackets space equals space 2 open square brackets straight pi over 4 cross times 1 minus 0 plus log fraction numerator 1 over denominator square root of 2 end fraction minus log space 1 close square brackets
equals space 2 open square brackets straight pi over 4 plus log space 1 space minus space log space square root of 2 close square brackets space equals space straight pi over 2 minus log space 2

    Question 132
    CBSEENMA12032542

    Evaluate the following:
    integral subscript 0 superscript 1 cos to the power of negative 1 end exponent open parentheses fraction numerator 1 minus straight x squared over denominator 1 plus straight x squared end fraction close parentheses dx




    Solution

    Let I = integral subscript 0 superscript 1 cos to the power of negative 1 end exponent open parentheses fraction numerator 1 minus straight x squared over denominator 1 plus straight x squared end fraction close parentheses dx
    Put x = tan θ so that dx = sec2 θ dθ When x = 0, tan θ = 1  ⇒ θ = 0
    When straight x space equals space 1 comma space space space tanθ space equals space 1                rightwards double arrow space space space straight theta space equals space straight pi over 4
    therefore space space space space straight I space equals space space integral subscript 0 superscript straight pi over 4 end superscript cos to the power of negative 1 end exponent open parentheses fraction numerator 1 minus tan squared straight theta over denominator 1 plus tan squared straight theta end fraction close parentheses. space sec squared straight theta space dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript cos to the power of negative 1 end exponent left parenthesis cos space 2 straight theta right parenthesis space. sec squared straight theta space dθ
               equals space integral subscript 0 superscript straight pi over 4 end superscript 2 space straight theta space sec squared straight theta space dθ space equals space 2 integral subscript 0 superscript straight pi over 4 end superscript straight theta. space sec squared straight theta space dθ
               equals space 2 open curly brackets open square brackets straight theta space tanθ close square brackets subscript 1 superscript straight pi over 4 end superscript minus integral subscript 0 superscript straight pi over 4 end superscript 1. space tanθ space dθ close curly brackets space equals space 2 open curly brackets open square brackets straight theta space tan space straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript plus open square brackets log space cosθ close square brackets subscript 0 superscript straight pi over 4 end superscript close curly brackets
                equals space 2 open curly brackets straight pi over 4 space tan straight pi over 4 minus 0 plus log space cos straight pi over 4 minus log space cos space 0 close curly brackets space equals space 2 open square brackets straight pi over 4 cross times 1 minus 0 plus log fraction numerator 1 over denominator square root of 2 end fraction minus log space 1 close square brackets
equals space 2 open square brackets straight pi over 4 plus log space 1 space minus space log space square root of 2 close square brackets space equals space straight pi over 2 minus log space 2
                  

    Question 133
    CBSEENMA12032543

    Evaluate the following:
    integral subscript 0 superscript 1 tan to the power of negative 1 end exponent open parentheses fraction numerator 2 straight x over denominator 1 minus straight x squared end fraction close parentheses dx





    Solution

    Let I = integral subscript 0 superscript 1 space tan to the power of negative 1 end exponent open parentheses fraction numerator 2 straight x over denominator 1 minus straight x squared end fraction close parentheses dx
    Put x = tan θ so that dx = sec2 θ dθ
    When x = 0, tan θ = 1    ⇒ θ = 0
    When straight x space equals space 1 comma space space tanθ space equals space 1 space space space space space space space space space space space space space space space space space space space space rightwards double arrow space space space straight theta space equals space straight pi over 4
    therefore            I = integral subscript 0 superscript straight pi over 4 end superscript space cos to the power of negative 1 end exponent open parentheses fraction numerator 2 space tan squared straight theta over denominator 1 minus tan squared straight theta end fraction close parentheses space. space sec squared straight theta space dθ
                      equals space integral subscript 0 superscript straight pi over 4 end superscript space tan to the power of negative 1 end exponent space left parenthesis tan space 2 straight theta right parenthesis space. sec squared straight theta space dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript space 2 straight theta space sec squared straight theta space dθ space equals space 2 space integral subscript 0 superscript straight pi over 4 end superscript straight theta. space sec squared straight theta space dθ
                       equals 2 open curly brackets open square brackets straight theta space tan space straight theta close square brackets subscript 1 superscript straight pi over 4 end superscript minus integral subscript 0 superscript straight pi over 4 end superscript 1. space tanθ space dθ close curly brackets space equals space 2 space open curly brackets open square brackets straight theta space tanθ close square brackets subscript 0 superscript straight pi over 4 end superscript plus open square brackets log space cosθ close square brackets subscript 0 superscript straight pi over 4 end superscript close curly brackets
space equals space 2 open curly brackets straight pi over 4 tan straight pi over 4 minus 0 plus log space cos straight pi over 4 minus log space cos 0 close curly brackets space equals 2 open square brackets straight pi over 4 cross times 1 minus 0 plus log fraction numerator 1 over denominator square root of 2 end fraction minus log space 1 close square brackets
space equals space 2 open square brackets straight pi over 4 plus log space 1 space minus log square root of 2 close square brackets space equals space straight pi over 2 minus log space 2

    Question 134
    CBSEENMA12032544

    Evaluate the following:
    integral subscript 0 superscript 2 straight pi end superscript straight e to the power of straight x space sin open parentheses straight pi over 4 plus straight x over 2 close parentheses dx.






    Solution

    Let
    straight I space equals space integral subscript 0 superscript 2 straight pi end superscript straight e to the power of straight x space sin open parentheses straight pi over 4 plus straight x over 2 close parentheses dx
    Put straight pi over 4 plus straight x over 2 space equals space straight t comma space space space space space space therefore space space space 1 half dx space equals space dt space space space space space space space rightwards double arrow space space space dx space equals space 2 space dt
    When straight x space equals space 0 comma space space space straight t space equals space straight pi over 4
    When straight x space equals space 2 straight pi comma space space space straight t space equals space fraction numerator 5 straight pi over denominator 4 end fraction
    therefore                   straight I space equals space integral subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript space straight e to the power of 2 straight t minus straight pi over 2 end exponent space sin space straight t space dt space equals space 2 space straight e to the power of straight pi over 2 end exponent integral subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript straight e to the power of 2 straight t end exponent space sint space dt
                       equals space 2 straight e to the power of negative straight pi over 2 end exponent. fraction numerator 1 over denominator 4 plus 1 end fraction open square brackets straight e to the power of 2 straight t end exponent left parenthesis 2 space sint space minus space cost right parenthesis close square brackets subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript
                        equals space space 2 over 5 straight e to the power of negative straight pi over 2 end exponent open square brackets straight e to the power of fraction numerator 5 straight pi over denominator 2 end fraction end exponent open parentheses 2 space sin space fraction numerator 5 straight pi over denominator 4 end fraction minus cos fraction numerator 5 straight pi over denominator 4 end fraction close parentheses space minus space straight e to the power of straight pi over 2 end exponent open parentheses 2 sin straight pi over 4 minus cos straight pi over 4 close parentheses close square brackets
space equals space 2 over 5 straight e to the power of negative straight pi over 2 end exponent space open square brackets straight e to the power of fraction numerator 5 space straight pi over denominator 2 end fraction end exponent open parentheses negative fraction numerator 2 over denominator square root of 2 end fraction plus fraction numerator 1 over denominator square root of 2 end fraction close parentheses space minus straight e to the power of straight pi over 2 end exponent open parentheses fraction numerator 2 over denominator square root of 2 end fraction minus fraction numerator 1 over denominator square root of 2 end fraction close parentheses close square brackets
space equals 2 over 5 open square brackets straight e to the power of 2 straight pi end exponent open parentheses negative fraction numerator 1 over denominator square root of 2 end fraction close parentheses minus fraction numerator 1 over denominator square root of 2 end fraction close square brackets space equals space minus fraction numerator square root of 2 over denominator 5 end fraction left parenthesis straight e to the power of 2 straight pi end exponent plus 1 right parenthesis

    Question 135
    CBSEENMA12032545

    Evaluate the following:
    integral subscript 1 superscript 2 open parentheses 1 over straight x minus fraction numerator 1 over denominator 2 straight x squared end fraction close parentheses space straight e to the power of 2 straight x end exponent dx






    Solution

    Let 
    straight I space equals space integral subscript 1 superscript 2 open parentheses 1 over straight x minus fraction numerator 1 over denominator 2 straight x squared end fraction close parentheses space straight e to the power of 2 straight x end exponent space dx
       equals space integral subscript 1 superscript 2 1 over straight x straight e to the power of 2 straight x end exponent dx space plus space integral fraction numerator negative 1 over denominator 2 straight x squared end fraction straight e to the power of 2 straight x end exponent dx
        equals space open square brackets 1 over straight x straight e to the power of 2 straight x end exponent over 2 close square brackets subscript 1 superscript 2 space minus space integral subscript 1 superscript 2 fraction numerator negative 1 over denominator straight x squared end fraction straight e to the power of 2 straight x end exponent over 2 dx plus integral subscript 1 superscript 2 fraction numerator negative 1 over denominator 2 straight x squared end fraction straight e to the power of 2 straight x end exponent dx  [integrating by parts]
          equals space 1 half open square brackets straight e to the power of 2 straight x end exponent over straight x close square brackets subscript 1 superscript 2 space minus space integral subscript 1 superscript 2 fraction numerator negative 1 over denominator 2 straight x squared end fraction straight e to the power of 2 straight x end exponent dx plus integral subscript 1 superscript 2 fraction numerator negative 1 over denominator 2 space straight x squared end fraction straight e to the power of 2 straight x end exponent dx
           equals space 1 half open square brackets straight e to the power of 4 over 2 minus straight e squared over 1 close square brackets space equals space 1 fourth left parenthesis straight e to the power of 4 minus 2 straight e squared right parenthesis space equals 1 fourth straight e squared left parenthesis straight e squared minus 2 right parenthesis

    Question 136
    CBSEENMA12032546

    Evaluate the following:
    integral subscript straight pi over 2 end subscript superscript straight pi straight e to the power of straight x open parentheses fraction numerator 1 minus sinx over denominator 1 minus cosx end fraction close parentheses dx







    Solution

    Let
    I = integral subscript straight pi over 2 end subscript superscript straight pi space straight e to the power of straight x open parentheses fraction numerator 1 minus sinx over denominator 1 minus cosx end fraction close parentheses dx space equals space integral subscript straight pi over 2 end subscript superscript straight pi straight e to the power of straight x open square brackets fraction numerator 1 minus 2 sin begin display style straight x over 2 end style cos begin display style straight x over 2 end style over denominator 2 space sin squared begin display style straight x over 2 end style end fraction close square brackets dx
       equals space integral subscript straight pi over 2 end subscript superscript straight pi straight e to the power of straight x open square brackets fraction numerator 1 over denominator 2 sin squared begin display style straight x over 2 end style end fraction minus fraction numerator 2 sin begin display style straight x over 2 end style cos begin display style straight x over 2 end style over denominator 2 sin squared begin display style straight x over 2 end style end fraction close square brackets space dx space equals space integral subscript straight pi over 2 end subscript superscript straight pi straight e to the power of straight x open square brackets 1 half cosec squared straight x over 2 minus cot straight x over 2 close square brackets dx
         equals space integral subscript straight pi over 2 end subscript superscript straight pi over 2 end superscript straight e to the power of straight x open square brackets negative cot space straight x over 2 plus 1 half cosec squared straight x over 2 close square brackets dx space equals space open square brackets straight e to the power of straight x open parentheses negative cot space straight x over 2 close parentheses close square brackets subscript straight pi over 2 end subscript superscript straight pi
                                                                 open square brackets because space space integral space straight e to the power of straight x left curly bracket straight f left parenthesis straight x right parenthesis space plus space straight f apostrophe left parenthesis straight x right parenthesis right curly bracket space dx space equals space straight e to the power of straight x space straight f left parenthesis straight x right parenthesis close square brackets
    equals space minus open square brackets straight e to the power of straight x space cot space straight x over 2 close square brackets subscript straight pi over 2 end subscript superscript straight pi space equals space minus open square brackets straight e to the power of straight pi space cot straight pi over 2 minus straight e to the power of straight pi over 2 end exponent space cot straight pi over 4 close square brackets space equals negative open square brackets straight e to the power of straight pi cross times 0 minus straight e to the power of straight pi over 2 end exponent cross times 1 close square brackets space equals space straight e to the power of straight pi over 2 end exponent

    Question 137
    CBSEENMA12032547

    Evaluate the following:
    integral subscript 0 superscript 2 straight pi end superscript space straight e to the power of straight x over 2 end exponent space sin space open parentheses straight x over 2 plus straight pi over 4 close parentheses dx








    Solution

    LetI = integral subscript 0 superscript 2 straight pi end superscript straight e to the power of straight x over 2 end exponent space sin space open parentheses straight x over 2 plus straight pi over 4 close parentheses space dx
    Put space straight x over 2 plus straight pi over 4 space equals space straight t comma space space space space space space space therefore space space 1 half dx space equals space dt space space space space space space space space space space rightwards double arrow space space dx space space equals space 2 space dt
    When    straight x space equals space 0 comma space space space straight t space space equals straight pi over 4
    When     straight x space equals space 2 straight pi comma space space space straight t space equals space fraction numerator 5 straight pi over denominator 4 end fraction
    therefore                  straight I space equals space 2 integral subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript space straight e to the power of straight t minus straight pi over 4 end exponent space sin space straight t space dt space equals space 2 straight e to the power of negative straight pi over 4 end exponent integral subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript space straight e to the power of straight t space sint space dt
                               equals space 2 space straight e to the power of negative straight pi over 4 end exponent open square brackets 1 half straight e to the power of straight t space left parenthesis sint space minus cost right parenthesis close square brackets subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript
    equals space straight e to the power of negative straight pi over 4 end exponent open square brackets straight e to the power of fraction numerator 5 straight pi over denominator 4 end fraction end exponent open parentheses sin space fraction numerator 5 straight pi over denominator 4 end fraction minus cos space fraction numerator 5 straight pi over denominator 4 end fraction close parentheses space minus space straight e to the power of straight pi over 4 end exponent open parentheses sin straight pi over 4 minus cos straight pi over 4 close parentheses close square brackets
space equals space straight e to the power of negative straight pi over 4 end exponent open square brackets straight e to the power of fraction numerator 5 straight pi over denominator 4 end fraction end exponent open parentheses negative fraction numerator 1 over denominator square root of 2 end fraction plus fraction numerator 1 over denominator square root of 2 end fraction close parentheses space minus space straight e to the power of straight pi over 4 end exponent open parentheses fraction numerator 1 over denominator square root of 2 end fraction minus fraction numerator 1 over denominator square root of 2 end fraction close parentheses close square brackets space equals space straight e to the power of straight pi over 4 end exponent left square bracket 0 minus 0 right square bracket space equals space 0

    Question 138
    CBSEENMA12032548

    Evaluate the following:
    integral subscript 0 superscript 2 straight pi end superscript straight e to the power of straight x cos open parentheses straight pi over 4 plus straight x over 2 close parentheses dx.

    Solution

    Let
    I = integral subscript 0 superscript 2 straight pi end superscript straight e to the power of straight x space cos open parentheses straight pi over 4 plus straight x over 2 close parentheses dx
    Put straight pi over 4 plus straight x over 2 space equals space straight t comma space space space space space space space therefore space space 1 half dx space equals space dt space space space space space space space space rightwards double arrow space space space dx space equals space 2 space dt
    When  straight x space equals space 0 comma space space space straight t space equals space straight pi over 4
    When   straight x space equals space 2 straight pi comma space space space straight t space equals space fraction numerator 5 straight pi over denominator 4 end fraction
    therefore       straight I space equals space 2 integral subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript straight e to the power of 2 straight t minus straight pi over 2 end exponent space cos space straight t space dt space equals space 2 space straight e to the power of negative straight pi over 2 end exponent integral subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript straight e to the power of 2 straight t end exponent space cost space dt space
                  equals space 2 space straight e to the power of negative straight pi over 2 end exponent. space fraction numerator 1 over denominator 4 plus 1 end fraction open square brackets straight e to the power of 2 straight t end exponent space left parenthesis 2 space cos space straight t space plus space sin space straight t close square brackets subscript straight pi over 4 end subscript superscript fraction numerator 5 straight pi over denominator 4 end fraction end superscript
                  equals space 2 over 5 straight e to the power of negative straight pi over 2 end exponent open square brackets straight e to the power of fraction numerator 5 straight pi over denominator 2 end fraction end exponent open parentheses 2 space cos space fraction numerator 5 straight pi over denominator 4 end fraction plus sin fraction numerator 5 straight pi over denominator 4 end fraction close parentheses space minus space straight e to the power of straight pi over 2 end exponent space open parentheses 2 space cos space straight pi over 4 plus sin straight pi over 4 close parentheses close square brackets
                     equals space 2 over 5 straight e to the power of negative straight pi over 2 end exponent space open square brackets straight e to the power of fraction numerator 5 straight pi over denominator 2 end fraction end exponent open parentheses negative fraction numerator 2 over denominator square root of 2 end fraction minus fraction numerator 1 over denominator square root of 2 end fraction close parentheses minus straight e to the power of straight pi over 2 end exponent open parentheses fraction numerator 2 over denominator square root of 2 end fraction plus fraction numerator 1 over denominator square root of 2 end fraction close parentheses close square brackets
equals space 2 over 5 straight e to the power of negative straight pi over 2 end exponent open square brackets negative fraction numerator 3 over denominator square root of 2 end fraction straight e to the power of fraction numerator 5 straight pi over denominator 2 end fraction end exponent minus fraction numerator 3 over denominator square root of 2 end fraction straight e to the power of straight pi over 2 end exponent close square brackets
space equals negative fraction numerator 3 square root of 2 over denominator 5 end fraction left parenthesis straight e to the power of 2 straight pi end exponent plus 1 right parenthesis

    Question 139
    CBSEENMA12032549

    The value of the integral integral subscript 1 third end subscript superscript 1 fraction numerator left parenthesis straight x minus straight x cubed right parenthesis to the power of begin display style 1 third end style end exponent over denominator straight x to the power of 4 end fraction dx

    • 6

    • 0

    • 3

    • 4

    Solution

    A.

    6

    Let  straight I space equals space integral subscript 1 third end subscript superscript 1 space fraction numerator left parenthesis straight x minus straight x cubed right parenthesis to the power of begin display style 1 third end style end exponent over denominator straight x to the power of 4 end fraction dx space equals space integral subscript 3 superscript 1 fraction numerator straight x open parentheses begin display style 1 over straight x squared end style minus 1 close parentheses to the power of begin display style 1 third end style end exponent over denominator straight x to the power of 4 end fraction dx space space space
           equals space integral subscript 1 third end subscript superscript 1 open parentheses begin display style 1 over straight x squared end style minus 1 close parentheses to the power of begin display style 1 third end style end exponent over straight x cubed dx space equals space integral subscript 1 third end subscript superscript 1 space open parentheses 1 over straight x squared minus 1 close parentheses to the power of 1 third end exponent. space 1 over straight x cubed dx
    Put 1 over straight x squared space equals space straight t comma space space space space space therefore space space space minus 2 over straight x cubed dx space equals space dt space space space rightwards double arrow space space space 1 over straight x cubed dx space equals space minus 1 half dt
    When straight x space equals space 1 third comma space space straight t space equals space 9
    When x = 1,  t = 1
    therefore                     straight I space equals negative 1 half integral subscript 9 superscript 1 left parenthesis straight t minus 1 right parenthesis to the power of 1 third end exponent dt space equals space minus 1 half open square brackets fraction numerator left parenthesis straight t minus 1 right parenthesis to the power of begin display style 4 over 3 end style end exponent over denominator begin display style 4 over 3 end style end fraction close square brackets subscript 0 superscript 1
                                equals negative 3 over 8 open square brackets left parenthesis straight t minus 1 right parenthesis to the power of 4 over 3 end exponent close square brackets subscript 9 superscript 1 space equals space minus 3 over 8 open square brackets left parenthesis 1 minus 1 right parenthesis to the power of 4 over 3 end exponent minus left parenthesis 9 minus 1 right parenthesis to the power of 4 over 3 end exponent close square brackets
space equals space minus 3 over 8 open square brackets 0 minus left parenthesis 8 right parenthesis to the power of 4 over 3 end exponent close square brackets space equals space 3 over 8 left parenthesis 2 cubed right parenthesis to the power of 4 over 3 end exponent space equals space 3 over 8 cross times 2 to the power of 4 space equals space 3 over 8 cross times 16 space equals space 6

    Question 140
    CBSEENMA12032550

    If straight f left parenthesis straight x right parenthesis space equals space integral subscript 0 superscript straight x space straight t space sin space straight t space dt comma space space then space straight f apostrophe left parenthesis straight x right parenthesis space is

    • cosx + x sin x

    • x sinx

    • x cosx

    • sinx + x cosx

    Solution

    B.

    x sinx

    f(x) = integral subscript 0 superscript straight x straight t space sin space straight t space dt
    ∴ f '(x) = x sin x       [∴ of first fundamental theorem]

    Question 141
    CBSEENMA12032551

    Evaluate integral subscript 0 superscript straight pi divided by 2 end superscript space sin squared straight x space dx

    Solution

    Let
    I = integral subscript 0 superscript straight pi divided by 2 end superscript sin squared xdx   ...(1)
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript sin squared open parentheses straight pi over 2 minus straight x close parentheses dx                          open square brackets because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space cos squared straight x space dx                                                 ...(2)
    Adding (1) and (2), we get.
        2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript left parenthesis sin squared straight x plus cos squared straight x right parenthesis space dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
    therefore space space space space 2 space straight I space equals space straight pi over 2 space space space space space space space rightwards double arrow space space space space straight I space equals space straight pi over 4

    Question 142
    CBSEENMA12032552

    By using the properties of definite integrals, evaluate the following:
    integral subscript 0 superscript straight pi over 2 end superscript space cos squared straight x space dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript space cos squared straight x space dx                       ...(1)
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript cos squared open parentheses straight pi over 2 minus straight x close parentheses dx                                open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore   straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space sin squared straight x space dx                                    ...(2)
    Adding (1) and (2), we get,
            2 I = integral subscript 0 superscript straight pi over 2 end superscript left parenthesis cos squared straight x plus sin squared straight x right parenthesis dx space equals space integral subscript 0 superscript straight pi over 2 end superscript 1 dx space equals space left square bracket straight x right square bracket subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0
    therefore space space 2 space straight I space equals space straight pi over 2 space space space rightwards double arrow space space space straight I space equals space straight pi over 4

    Question 143
    CBSEENMA12032553

    By using the properties of definite integrals, evaluate the following:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx                        ...(1)
    Then straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space space space space space open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin to the power of 5 straight x over denominator cos to the power of 5 straight x plus sin to the power of 5 straight x end fraction dx                     ...(2)
    Adding (1) and (2), we get.
    2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open parentheses fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction plus fraction numerator sin to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction close parentheses dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin to the power of 5 straight x plus cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript 1 space dx
           equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0
     2 space straight I space equals space straight pi over 2 space space space space rightwards double arrow space space space space straight I space equals space straight pi over 4

    Question 144
    CBSEENMA12032554

    By using the properties of definite integrals, evaluate the following:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cosx over denominator square root of cosx plus square root of sinx end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x space end root plus square root of sin space straight x end root end fraction dx                                  ...(1)
    Then straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end root end fraction dx
                                                                                                  open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx                               ...(2)
    Adding (1) and (2), we get,
              2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space open square brackets fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction plus fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction close square brackets dx
space space space space space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cos space straight x end root plus square root of sin space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript space 1. space dx
space space space space space space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space straight pi over 2 minus 0
    therefore space space space 2 space space straight I space space equals space straight pi over 2                          rightwards double arrow space space space straight I space equals space straight pi over 4

    Question 145
    CBSEENMA12032555

    Prove that: integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus tanx end fraction space equals space straight pi over 4.

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus tanx end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus begin display style fraction numerator sinx space over denominator cosx end fraction end style end fraction dx
    therefore space space space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cosx over denominator cosx plus sinx end fraction dx                              ...(1)
                  equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space space space open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis dx close square brackets
     therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x over denominator sin space straight x space plus space cos space straight x space end fraction dx                               ...(2)
    Adding (1) and (2), we get,
                          2 straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open parentheses fraction numerator cos space straight x over denominator cos space straight x space plus space sin space straight x end fraction plus fraction numerator sin space straight x over denominator sin space straight x space plus space cos space straight x end fraction close parentheses dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cosx plus sinx over denominator cosx plus sinx end fraction dx space equals integral subscript 0 superscript straight pi over 2 end superscript 1 space dx
          equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals straight pi over 2 minus 0
    therefore space space space space space 2 straight I space equals space straight pi over 2 space space space space space space space space space space rightwards double arrow space space space 1 space equals space straight pi over 4

    Question 146
    CBSEENMA12032556

    Evaluate the following:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus tan cubed straight x end fraction.

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus tan cubed straight x end fraction                                  ...(1)
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus tan cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction                 open square brackets because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space space equals integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
              equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus cot cubed straight x end fraction space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus begin display style 1 over tan cubed end style straight x end fraction
                          ...(2)
    Adding (1) and (2), we get.
                 
                       equals space integral subscript 0 superscript straight pi over 2 end superscript space 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space straight pi over 2 minus 0 space equals straight pi over 2
       space therefore space space space 2 space straight I space equals space straight pi over 2 comma space space space space straight I space equals space straight pi over 4
therefore space space space integral subscript 0 superscript straight pi over 2 end superscript space fraction numerator dx over denominator 1 plus tan cubed straight x end fraction space equals space straight pi over 4

    Question 147
    CBSEENMA12032557

    Evaluate: integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus tan to the power of 5 straight x end fraction dx

    Solution

    Let I = straight I space equals integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus tan to the power of 5 straight x end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus begin display style fraction numerator sin to the power of 5 straight x over denominator cos to the power of 5 straight x end fraction end style end fraction dx
    therefore space space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos to the power of 5 straight x over denominator cos to the power of 5 straight x plus sin to the power of 5 straight x end fraction dx                                 ...(1)
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator cos to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus sin to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction space open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
                                 ...(2)
    Adding (1) and (2), we get,
    therefore space space space space space space space space space space 2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open parentheses fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction plus fraction numerator sin to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction close parentheses dx
                       space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin to the power of 5 straight x plus cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript space 1 space dx space space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space straight pi over 2 minus 0
therefore space space space space space 2 space space space straight I space space equals space straight pi over 2 space space space space space rightwards double arrow space space space space straight I space equals space straight pi over 4
                       

    Question 148
    CBSEENMA12032558

    Evaluate integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus cot cubed straight x end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus cot cubed straight x end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus begin display style fraction numerator cos cubed straight x over denominator sin cubed straight x end fraction end style end fraction dx
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin cubed straight x over denominator sin cubed straight x plus cos cubed straight x end fraction dx                     ...(1)
    rightwards double arrow space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos cubed straight x over denominator cos cubed straight x plus sin cubed straight x end fraction dx                      ...(2)
    Adding (1) and (2), we get.
                              2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin cubed straight x plus cos cubed straight x over denominator sin cubed straight x plus cos cubed straight x end fraction dx
    therefore                    2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript 1 space dx space space space rightwards double arrow space space space space space 2 space straight I space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript
    therefore space space space space space 2 space straight I space equals space straight pi over 2 minus 0 space space space rightwards double arrow space space straight I space equals space straight pi over 4

    Question 149
    CBSEENMA12032559

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x over denominator sin space straight x plus space cos space straight x end fraction dx space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin space straight x over denominator sin space straight x space plus space cos space straight x end fraction dx                                   ...(1)
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction space space space space space space space open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx space space space close square brackets
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cosx over denominator cosx plus sinx end fraction dx                                     ...(2)
    Adding (1) and (2), we get
     2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator sin space straight x over denominator sin space straight x plus space cos space straight x end fraction plus fraction numerator cosx over denominator cosx plus sinx end fraction close square brackets dx
           equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sinx plus cosx over denominator sinx plus cosx end fraction dx space equals integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
    therefore space space 2 space space straight I space equals space space straight pi over 2 space space space space space rightwards double arrow space space space space space space straight I space equals space straight pi over 4

    Question 150
    CBSEENMA12032560

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of sinx over denominator square root of sinx plus square root of cosx end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of sinx over denominator square root of sinx plus square root of cosx end fraction dx                     ...(1)
    Then straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root plus square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end fraction dx space space space open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of cosx over denominator square root of cosx plus square root of sinx end fraction dx                     ...(2)
    Adding (1) and (2), we get,
     2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator square root of sinx over denominator square root of sinx plus square root of cosx end fraction plus fraction numerator square root of cosx over denominator square root of cosx plus square root of sinx end fraction close square brackets dx
space space space space space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space fraction numerator square root of sinx plus square root of cosx over denominator square root of sinx plus square root of cosx end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
therefore space space space 2 space straight I space equals space straight pi over 2 space space space space space space space space rightwards double arrow space space space space space straight I space equals space straight pi over 4

    Question 151
    CBSEENMA12032561

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin cubed straight x over denominator sin cubed straight x plus cos cubed straight x end fraction dx space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin cubed straight x over denominator sin cubed straight x plus cos cubed straight x end fraction dx                          ...(1)
    Then I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos cubed open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx    open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space fraction numerator cos cubed straight x over denominator cos cubed straight x plus sin cubed straight x end fraction dx                           ...(2)
    Adding (1) and (2), we get,
           2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator sin cubed straight x over denominator sin cubed straight x plus cos cubed straight x end fraction plus fraction numerator cos cubed straight x over denominator cos cubed straight x plus sin cubed straight x end fraction close square brackets dx
space space space space space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin cubed straight x plus cos cubed straight x over denominator sin cubed straight x plus cos cubed straight x end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
therefore space space space 2 space straight I space equals space straight pi over 2 space space space space rightwards double arrow space space space space space space space straight I space equals space straight pi over 4

    Question 152
    CBSEENMA12032562

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript space fraction numerator sin to the power of 4 straight x over denominator sin to the power of 4 straight x plus cos to the power of 4 straight x end fraction dx space equals space straight pi over 4

    Solution

    Let I =integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 4 straight x over denominator sin to the power of 4 straight x plus cos to the power of 4 straight x end fraction dx                         ...(1) 
    Then I = integral subscript 0 superscript straight pi divided by 2 end superscript space fraction numerator sin to the power of 4 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin to the power of 4 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos to the power of 4 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx    open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos to the power of 4 straight x over denominator cos to the power of 4 straight x plus sin to the power of 4 straight x end fraction dx                   ...(2)

    Adding (1) and (2), we get.
              2 space straight I space equals integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator sin to the power of 4 space straight x over denominator sin to the power of 4 straight x plus cos to the power of 4 straight x end fraction plus fraction numerator cos to the power of 4 straight x over denominator cos to the power of 4 straight x plus sin to the power of 4 straight x end fraction close square brackets space dx
space space space space space equals integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 4 straight x plus cos to the power of 4 straight x over denominator sin to the power of 4 straight x plus cos to the power of 4 straight x end fraction space dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals straight pi over 2 minus 0 space equals space straight pi over 2
therefore space space 2 space straight I space equals space straight pi over 2 space space space space space space space space space space rightwards double arrow space space space space space straight I space equals space straight pi over 4

    Question 153
    CBSEENMA12032563

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx space equals space straight pi over 4


    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx                         ...(1)
    Then straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos to the power of 5 open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space space open square brackets because integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 5 straight x over denominator cos to the power of 5 straight x plus sin to the power of 5 straight x end fraction dx                      ...(2)
    Adding (1) and (2) we get,
    2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction plus fraction numerator sin to the power of 5 straight x over denominator cos to the power of 5 straight x plus sin to the power of 5 straight x end fraction close square brackets dx
space space space space space space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 5 straight x plus cos to the power of 5 straight x over denominator sin to the power of 5 straight x plus cos to the power of 5 straight x end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
therefore space space 2 space straight I space equals space fraction numerator straight pi over denominator 2 space end fraction space space space space space space space rightwards double arrow space space space space space space space space straight I space equals space straight pi over 4

    Question 154
    CBSEENMA12032564

    Evaluate:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin to the power of begin display style 3 over 2 end style end exponent straight x over denominator sin to the power of begin display style 3 over 2 end style end exponent straight x plus cos to the power of begin display style 3 over 2 end style end exponent straight x end fraction dx space

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 3 divided by 2 end exponent straight x over denominator sin to the power of 3 divided by 2 end exponent straight x plus cos to the power of 3 divided by 2 end exponent straight x end fraction dx                        ...(1)
    Then straight I space equals integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 3 divided by 2 end exponent open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin to the power of 3 divided by 2 end exponent open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos to the power of 3 divided by 2 end exponent open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx    open square brackets because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space space equals integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos to the power of 3 divided by 2 end exponent straight x over denominator cos to the power of 3 divided by 2 end exponent straight x plus sin to the power of 3 divided by 2 end exponent straight x end fraction dx.                        ...(2)
    Adding (1) and (2), we get,
       2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator sin to the power of 3 divided by 2 end exponent straight x over denominator sin to the power of 3 divided by 2 end exponent straight x plus cos to the power of 3 divided by 2 end exponent straight x end fraction plus fraction numerator cos to the power of 3 divided by 2 end exponent straight x over denominator cos to the power of 3 divided by 2 end exponent straight x plus sin to the power of 3 divided by 2 end exponent straight x end fraction close square brackets dx
               equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 3 divided by 2 end exponent straight x plus cos to the power of 3 divided by 2 end exponent straight x over denominator sin to the power of 3 divided by 2 end exponent straight x plus cos to the power of 3 divided by 2 end exponent straight x end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
     therefore space space space 2 space straight I space equals space straight pi over 2 space space space space space space space rightwards double arrow space space space space space space space straight I space equals space straight pi over 4

    Question 155
    CBSEENMA12032565

    Evaluate:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin to the power of begin display style 5 over 3 end style end exponent straight x over denominator sin to the power of begin display style 5 over 3 end style end exponent straight x plus cos to the power of begin display style 5 over 3 end style end exponent straight x end fraction dx space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 5 divided by 3 end exponent straight x over denominator sin to the power of 5 divided by 3 end exponent straight x plus cos to the power of 5 divided by 3 end exponent straight x end fraction dx                     ...(1)
    Then I =integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 5 divided by 3 end exponent open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin to the power of 5 divided by 3 end exponent open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos to the power of 5 divided by 3 end exponent open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx             open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos to the power of 5 divided by 3 end exponent straight x over denominator cos to the power of 5 divided by 3 end exponent straight x plus sin to the power of 5 divided by 3 end exponent straight x end fraction dx                  ...(2)
    Adding (1) and (2)
         2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator sin to the power of 5 divided by 3 end exponent straight x over denominator sin to the power of 5 divided by 3 end exponent straight x plus cos to the power of 5 divided by 3 end exponent straight x end fraction plus fraction numerator cos to the power of 5 divided by 3 end exponent straight x over denominator cos to the power of 5 divided by 3 end exponent straight x plus sin to the power of 5 divided by 3 end exponent straight x end fraction close square brackets dx
space space space space space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin to the power of 5 divided by 3 end exponent straight x plus cos to the power of 5 divided by 3 end exponent straight x over denominator sin to the power of 5 divided by 3 end exponent straight x plus cos to the power of 5 divided by 3 end exponent straight x end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
therefore space space 2 space straight I space equals space straight pi over 2 space space space space space space rightwards double arrow space space space space space straight I space equals space straight pi over 4

    Question 156
    CBSEENMA12032566

    Evaluate:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cotx over denominator square root of tanx plus square root of cotx end fraction dx space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of cot space straight x end root over denominator square root of cot space straight x end root plus square root of tan space straight x end root end fraction dx                    ...(1)
    Then I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of cot open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of cot open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus square root of tan open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end root end fraction dx    open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of tan space straight x end root over denominator square root of tan space straight x end root plus square root of cot space straight x end root end fraction dx                 ....(2)
    Adding (1) and (2), we get,
                     2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator square root of cot space straight x end root over denominator square root of cot space straight x end root plus square root of tan space straight x end root end fraction plus fraction numerator square root of tan space straight x end root over denominator square root of tan space straight x end root plus square root of cot straight x end fraction close square brackets dx
                          equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of cot space straight x end root space plus space square root of tan space straight x over denominator square root of cot space straight x end root end fraction dx space equals space space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
    therefore space space space space 2 space straight I space equals space straight pi over 2 space space space space space space space rightwards double arrow space space space space space space space straight I space space space equals space straight pi over 4

    Question 157
    CBSEENMA12032567

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus cot space straight x end fraction space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator dx over denominator 1 plus cot space straight x end fraction space equals integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus begin display style cosx over sinx end style end fraction space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x over denominator sin space straight x space plus space cos space straight x end fraction dx              ...(1)
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx    open square brackets because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cosx over denominator cosx space plus space sinx end fraction dx                                                                           ...(2)
    Adding (1) and (2), we get.
     2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin space straight x over denominator sin space straight x plus space cos space straight x end fraction plus fraction numerator cos space straight x over denominator cos space straight x space plus space sin space straight x end fraction dx
            equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sinx space plus space cosx over denominator sinx space plus space cosx end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
    therefore space space 2 space straight I space space equals space straight pi over 2 space space space space space space space space rightwards double arrow space space space space space space straight I space equals space space straight pi over 4

    Question 158
    CBSEENMA12032568

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus square root of tan space straight x end root end fraction space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus square root of tan space straight x end root end fraction space equals space integral fraction numerator square root of cos space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx            ...(1)
    Then I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root plus square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end fraction dx
                                                                  open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cosx end fraction dx                                        ...(2)
    Adding (1) and (2), we get,
                          2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open square brackets fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x space end root plus square root of sin space straight x end root end fraction plus fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction close square brackets dx
space space space space space space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of cos space straight x end root plus square root of sin space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript 1. space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space straight pi over 2 minus 0
    therefore space space 2 space straight I space space equals space straight pi over 2 space space space space space space space rightwards double arrow space space space space space space straight I space equals space straight pi over 4

    Question 159
    CBSEENMA12032569

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus square root of cot space straight x end root end fraction space equals space straight pi over 4


    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator 1 plus square root of cot straight x end fraction space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x space end root plus square root of cos space straight x end root end fraction dx                 ...(1)
    Then I = integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root plus square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end fraction dx   open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction dx                                                  ...(2)
    Adding (1) and (2), we get,
    2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript open square brackets fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction plus fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction close square brackets dx
          equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator square root of sin space straight x end root plus square root of cos space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
    therefore space space 2 space straight I space equals space straight pi over 2 space space space space space space space space space space space space space space space space rightwards double arrow space space space space straight I space equals space straight pi over 4

    Question 160
    CBSEENMA12032570

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos space straight x over denominator sin space straight x space plus space cos space straight x end fraction dx


    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos space straight x over denominator sin space straight x plus space cos space straight x end fraction dx                     ...(1)
    Then straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space space space space open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space straight x over denominator cosx plus sinx end fraction                             ...(2)
    Adding (1) and (2), we get.
                     2 straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open parentheses fraction numerator cos space straight x over denominator sin space straight x space plus space cos space straight x space end fraction plus fraction numerator sin space straight x over denominator sin space straight x plus space cos space straight x end fraction close parentheses dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cosx plus sinx over denominator sinx plus cosx end fraction dx space equals integral subscript 0 superscript straight pi over 2 end superscript 1 space dx
                          equals space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2.
    therefore space space space space space space 2 space space straight I space space equals space space straight pi over 2 space space space space space space space space space rightwards double arrow space space space space straight I space equals space straight pi over 4
                          

    Question 161
    CBSEENMA12032571

    Evaluate integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator dx over denominator 1 plus square root of tanx end fraction

    Solution

    Let I = integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator 1 over denominator 1 plus square root of tan space straight x end root end fraction dx space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator 1 over denominator 1 plus begin display style fraction numerator square root of sin space straight x end root over denominator square root of cosx end fraction end style end fraction dx
    therefore space space space straight I space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction dx                               ....(1)
    Then I = integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of cos space open parentheses begin display style straight pi over 3 end style plus begin display style straight pi over 6 end style minus straight x close parentheses end root over denominator square root of cos space open parentheses begin display style straight pi over 3 end style plus begin display style straight pi over 6 end style minus straight x close parentheses end root plus square root of sin space open parentheses begin display style straight pi over 3 end style plus begin display style straight pi over 6 end style minus straight x close parentheses end root end fraction dx
                                                                       open square brackets because space space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f left parenthesis straight a plus straight b minus straight x right parenthesis space dx close square brackets
                       equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root plus square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end fraction dx
    therefore space space space straight I space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx                                  ...(2)
    Adding (1) and (2), we get.
                    2 space straight I space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript open square brackets fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction plus fraction numerator square root of sin space straight x end root over denominator square root of cosx plus square root of sin space straight x end root end fraction close square brackets dx
                         equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of cos space straight x end root plus square root of sin space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction dx space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript straight pi divided by 6 end subscript superscript straight pi divided by 3 end superscript space equals space straight pi over 3 minus straight pi over 6 space equals space fraction numerator 2 straight pi minus straight pi over denominator 6 end fraction
    therefore space space 2 space space straight I space equals space straight pi over 6 space space space space rightwards double arrow space space space straight I space space equals space straight pi over 12

    Question 162
    CBSEENMA12032572

    Evaluate integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx

    Solution

    Let I = integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx                               ...(1)
    Then I = integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of sin space open parentheses begin display style straight pi over 3 end style plus begin display style straight pi over 6 end style minus straight x close parentheses end root over denominator square root of sin space open parentheses begin display style straight pi over 3 end style plus begin display style straight pi over 6 end style minus straight x close parentheses end root plus square root of cos space open parentheses begin display style straight pi over 3 end style plus begin display style straight pi over 6 end style minus straight x close parentheses end root end fraction dx
                                                                        open square brackets because space space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f left parenthesis straight a plus straight b minus straight x right parenthesis space dx close square brackets
                   equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root over denominator square root of sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root plus square root of cos space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end root end fraction dx
    therefore space space space straight I space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of cos space straight x end root over denominator square root of cos space straight x end root plus square root of sin space straight x end root end fraction dx                              ...(2)
    Adding (1) and (2), we get,
      2 space straight I space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript open square brackets fraction numerator square root of sin space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction plus negative fraction numerator square root of cos space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction close square brackets dx
            equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript fraction numerator square root of sin space straight x end root plus square root of cos space straight x end root over denominator square root of sin space straight x end root plus square root of cos space straight x end root end fraction dx space equals space integral subscript straight pi over 6 end subscript superscript straight pi over 3 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript straight pi divided by 6 end subscript superscript straight pi divided by 3 end superscript space equals space straight pi over 3 minus straight pi over 6 space equals fraction numerator 2 straight pi minus straight pi over denominator 6 end fraction
    therefore space space 2 space straight I space equals space straight pi over 6 space space space rightwards double arrow space space straight I space equals space straight pi over 12

    Question 163
    CBSEENMA12032573

    Evaluate integral subscript 0 superscript straight pi space sin squared straight x space cos cubed straight x space dx.

    Solution

    Let I = integral subscript 0 superscript straight pi sin squared straight x space cos cubed straight x space dx space equals space integral subscript 0 superscript straight pi straight f left parenthesis straight x right parenthesis space dx
    where f(x) = sin squared straight x space cos cubed straight x
    Now straight f left parenthesis straight pi minus straight x right parenthesis space equals space sin squared left parenthesis straight pi minus straight x right parenthesis space cos cubed left parenthesis straight pi minus straight x right parenthesis space equals space minus sin squared straight x space cos cubed straight x
    therefore space space space straight f left parenthesis straight pi minus straight x right parenthesis space space equals negative straight f left parenthesis straight x right parenthesis
    therefore space space space integral subscript 0 superscript straight pi sin squared straight x space cosx space dx space equals space 0 space space space space space open square brackets because space space if space straight f left parenthesis 2 straight a minus straight x right parenthesis space equals space minus straight f left parenthesis straight x right parenthesis comma space then space integral subscript straight a superscript 2 straight a end superscript straight f left parenthesis straight x right parenthesis space dx space equals space 0 close square brackets

    Question 164
    CBSEENMA12032574

    Evaluate integral subscript negative straight pi over 4 end subscript superscript straight pi over 4 end superscript space sin squared straight x space dx

    Solution

    Let I = integral subscript straight pi over 4 end subscript superscript straight pi over 4 end superscript sin squared straight x space dx space equals space 2 integral subscript 0 superscript straight pi over 4 end superscript sin squared straight x space dx
    [∵ sin2 x is an even function as sin2 (–x) = sin2 x]
    equals space integral subscript 0 superscript straight pi over 4 end superscript space space 2 space sin squared straight x space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript left parenthesis 1 minus cos space 2 straight x right parenthesis space dx space equals space open square brackets straight x minus fraction numerator sin space 2 straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 4 end superscript
equals space open parentheses straight pi over 4 minus 1 half sin straight pi over 2 close parentheses space minus space open parentheses 0 minus 1 half sin space 0 close parentheses
space equals space open parentheses straight pi over 4 minus 1 half close parentheses space minus space space left parenthesis 0 space minus space 0 right parenthesis space equals space straight pi over 4 minus 1 half

    Question 165
    CBSEENMA12032575

    Evaluate integral subscript negative straight pi over 4 end subscript superscript straight pi over 4 end superscript cos squared xdx

    Solution

    Let I = integral subscript negative straight pi over 4 end subscript superscript straight pi over 4 end superscript cos squared straight x space dx space equals space 2 integral subscript 0 superscript straight pi over 4 end superscript cos squared straight x space dx
                                                           [because space cos squared straight x is an even function as cos squared left parenthesis negative straight x right parenthesis space equals space cos squared straight x]
            equals space integral subscript 0 superscript straight pi over 4 end superscript 2 space cos squared straight x space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript left parenthesis 1 plus cos 2 straight x right parenthesis space dx space equals space open square brackets straight x plus fraction numerator sin 2 straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 4 end superscript
equals space open parentheses straight pi over 4 plus 1 half sin straight pi over 2 close parentheses space minus space open parentheses 0 plus 1 half sin space 0 close parentheses
space equals space open parentheses straight pi over 4 plus 1 half cross times 1 close parentheses space minus space open parentheses 0 plus 1 half cross times 0 close parentheses space equals space straight pi over 4 plus 1 half

    Question 166
    CBSEENMA12032576

    By using the properties of definite integrals, evaluate
    integral subscript negative straight pi over 2 end subscript superscript straight pi over 2 end superscript cosx space dx

    Solution

    Let
    straight I space equals space integral subscript negative straight pi over 2 end subscript superscript straight pi over 2 end superscript cosx space dx space equals space 2 integral subscript 0 superscript straight pi over 2 end superscript space cosx space dx
    [∴ cos x is an even function as cos (–x) = cos x]
    equals space 2 open square brackets sin space straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space 2 open parentheses sin straight pi over 2 minus sin space 0 close parentheses space equals space 2 space left parenthesis 1 minus 0 right parenthesis space equals space 2.

    Question 167
    CBSEENMA12032577

    Evaluate integral subscript negative 1 end subscript superscript 1 sin to the power of 5 straight x space cos to the power of 4 straight x space dx

    Solution

    Comparing integral subscript negative 1 end subscript superscript 1 space sin to the power of 5 straight x space cos to the power of 4 straight x space dx space with space integral subscript negative 1 end subscript superscript 1 space straight f left parenthesis straight x right parenthesis space dx comma space space we space get
    f (x) = sin5 x cos4 x
    Now f (–x) = sin5 (–x) cos4 (–x) = – sinx cos4 x = – f (x)
    ∴ f (x) is an odd function
    therefore space space space space straight I space equals space 0                     [integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 0 space space if space straight f left parenthesis straight x right parenthesis is an odd function]
    therefore space space space integral subscript negative 1 end subscript superscript 1 space sin to the power of 5 straight x space cos to the power of 4 straight x space dx space equals space 0

    Question 168
    CBSEENMA12032578

    Evaluate integral subscript negative 1 end subscript superscript 1 space straight x to the power of 17 space cos to the power of 4 straight x space dx.

    Solution

    Comparing integral subscript negative 1 end subscript superscript 1 straight x to the power of 17 space cos to the power of 4 straight x space dx space with space integral subscript negative 1 end subscript superscript 1 straight f left parenthesis straight x right parenthesis space dx comma space we space get comma
              straight f left parenthesis straight x right parenthesis space equals space straight x to the power of 17 space cos to the power of 4 straight x
    Now straight f left parenthesis negative straight x right parenthesis space equals space left parenthesis negative straight x right parenthesis to the power of 17 space cos to the power of 4 colon left parenthesis negative straight x right parenthesis space equals space minus straight x to the power of 17 space cos to the power of 4 straight x space equals space space minus straight f left parenthesis straight x right parenthesis
    therefore space space space space straight f left parenthesis straight x right parenthesis space is space an space odd space function
    therefore space space space space space straight I space equals space 0 space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space integral subscript negative straight a end subscript superscript straight a straight f vertical line left parenthesis straight x right parenthesis space dx space equals space 0 space if space straight f space is space an space odd space function close square brackets
    therefore space space space space integral subscript negative 1 end subscript superscript 1 space straight x to the power of 17 space cos to the power of 4 straight x space dx space equals space 0

    Question 169
    CBSEENMA12032579

    Evaluate  integral subscript negative 1 end subscript superscript 1 space log space open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses dx.

    Solution
    integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space minus integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space space plus integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx
    rightwards double arrow space space space integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 0
    Let  straight I space equals space integral subscript negative 1 end subscript superscript 1 space log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses dx
    Let   straight f left parenthesis straight x right parenthesis space equals space log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses
    therefore space space space straight f left parenthesis negative straight x right parenthesis space equals space log open parentheses fraction numerator 2 minus straight x over denominator 2 plus straight x end fraction close parentheses space equals space log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses to the power of negative 1 end exponent space equals space minus log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses space equals space minus straight f left parenthesis straight x right parenthesis
therefore space space space space space space space straight f left parenthesis straight x right parenthesis space is space an space odd space function space of space straight x
    therefore space space space straight I space equals space 0 space space space space space space space space space space space space open square brackets because space space integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 0 space space if space straight f left parenthesis straight x right parenthesis space is space an space odd space function space of space straight x close square brackets
    Question 170
    CBSEENMA12032580

    Evaluate  integral subscript negative 8 end subscript superscript 8 space log space open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses dx.

    Solution
    integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space minus integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space plus space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx
    rightwards double arrow space space space integral subscript negative straight a end subscript superscript straight a space straight f left parenthesis straight x right parenthesis space dx space equals space 0
    Let                         straight I space equals space integral subscript negative 8 end subscript superscript 8 space log space open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses dx

    Let           straight f left parenthesis straight x right parenthesis space equals space log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses
    therefore space space space straight f left parenthesis negative straight x right parenthesis space equals space log open parentheses fraction numerator 2 minus straight x over denominator 2 plus straight x end fraction close parentheses space equals space log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses to the power of negative 1 end exponent space equals space minus log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses space equals space minus straight f left parenthesis straight x right parenthesis
    therefore space space space space space space straight f left parenthesis straight x right parenthesis  is an odd function of x.
    therefore space space space space space straight I equals space 0                           open square brackets because space integral subscript straight a superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 0 space if space straight f left parenthesis straight x right parenthesis space is space an space odd space function space of space straight x close square brackets
    Question 171
    CBSEENMA12032581

    Evaluate  integral subscript negative 2 end subscript superscript 2 space log space open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses space dx.

    Solution
    integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space minus integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx plus integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx
    rightwards double arrow  integral subscript negative straight a end subscript superscript straight a space straight f left parenthesis straight x right parenthesis space dx space equals space 0
     Let I =   integral subscript negative 2 end subscript superscript 2 space log space open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses dx
    Let    straight f left parenthesis straight x right parenthesis space equals space log space open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses
    therefore space space space space space straight f left parenthesis negative straight x right parenthesis space equals space log open parentheses fraction numerator 2 minus straight x over denominator 2 plus straight x end fraction close parentheses space equals space log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses to the power of negative 1 end exponent space equals space minus log open parentheses fraction numerator 2 plus straight x over denominator 2 minus straight x end fraction close parentheses space equals space minus straight f left parenthesis straight x right parenthesis
    therefore space space space space straight f left parenthesis straight x right parenthesis space is space an space odd space function space of space straight x
    therefore space space space space space straight I space equals space 0 space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space space space integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 0 space if space straight f left parenthesis straight x right parenthesis space is space an space odd space function space of space straight x close square brackets
    Question 172
    CBSEENMA12032582

    Show that
    integral subscript 0 superscript straight pi over 2 end superscript space sin squared straight x space dx space equals space straight pi over 4

    Solution

    Let I =  integral subscript 0 superscript straight pi divided by 2 end superscript sin squared straight x space dx                                             ...(1)
    therefore space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript sin squared open parentheses straight pi over 2 minus straight x close parentheses dx                     open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript cos squared straight x space dx                                         ...(2)
    Adding (1) and (2). we get.
              2 space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript left parenthesis sin squared straight x space plus cos squared straight x right parenthesis space dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript 1 space dx space equals space open square brackets straight x close square brackets subscript 0 superscript straight pi divided by 2 end superscript space equals space straight pi over 2 minus 0 space equals space straight pi over 2
    therefore space space space 2 space space straight I space equals space straight pi over 2 space space space space space space space rightwards double arrow space space space space straight I space equals space straight pi over 4

    Question 173
    CBSEENMA12032583

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript 2 straight pi end superscript cos to the power of 5 straight x space dx

    Solution

    Let I = integral subscript 0 superscript 2 straight pi end superscript cos to the power of 5 straight x space dx space equals space 2 integral subscript 0 superscript straight pi cos to the power of 5 straight x space dx
                                              open square brackets because space space cos to the power of 5 space left parenthesis 2 straight pi minus straight x right parenthesis space equals space cos to the power of 5 straight x
and space integral subscript 0 superscript 2 straight a end superscript straight f left parenthesis straight x right parenthesis space dx space equals space 2 integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space if space straight f left parenthesis 2 straight a minus straight x right parenthesis space equals space straight f left parenthesis straight x right parenthesis close square brackets
equals space 0 space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets table row cell because space cos to the power of 5 left parenthesis straight pi minus straight x right parenthesis space equals space left parenthesis negative cos to the power of 5 straight x right parenthesis space equals space minus cos to the power of 5 straight x end cell row cell and space integral subscript 0 superscript 2 straight a end superscript straight f left parenthesis straight x right parenthesis space dx space equals space 0 space if space straight f left parenthesis 2 straight a minus straight x right parenthesis space equals space minus straight f left parenthesis straight x right parenthesis end cell end table close square brackets space space space space space space space space space space space space space space space space space space space space space

    Question 174
    CBSEENMA12032584

    Show that:
    integral subscript negative straight pi over 2 end subscript superscript straight pi over 4 end superscript space sin to the power of 7 straight x space dx space equals space 0

    Solution

    Let I = integral subscript negative straight pi divided by 2 end subscript superscript straight pi divided by 2 end superscript space sin to the power of 7 straight x space dx
    Comparing  integral subscript negative straight pi divided by 2 end subscript superscript straight pi divided by 2 end superscript space sin to the power of 7 space straight x space dx space space with space integral subscript negative straight pi divided by 2 end subscript superscript straight pi divided by 2 end superscript space straight f left parenthesis straight x right parenthesis space dx comma space we space get
                straight f left parenthesis straight x right parenthesis space equals space sin to the power of 7 straight x
    Now  straight f left parenthesis negative straight x right parenthesis space equals space sin to the power of 7 left parenthesis negative straight x right parenthesis space equals space minus sin to the power of 7 straight x space equals space minus straight f left parenthesis straight x right parenthesis
    therefore space space space straight f left parenthesis straight x right parenthesis space is space an space odd space function
    therefore space space space straight I space equals space 0 space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 0 space if space straight f left parenthesis straight x right parenthesis space is space an space odd space function close square brackets

    Question 175
    CBSEENMA12032585

    Show that:
    integral subscript negative straight pi over 4 end subscript superscript straight pi over 4 end superscript straight x cubed space space cos cubed straight x space dx space equals 0

    Solution

    Let I = integral subscript negative straight pi divided by 4 end subscript superscript straight pi divided by 4 end superscript straight x cubed space cos cubed straight x space dx
    Let f(x) = straight x cubed space cos cubed straight x
    therefore space space space space space straight f left parenthesis negative straight x right parenthesis space equals space left parenthesis negative straight x right parenthesis cubed space cos cubed left parenthesis negative straight x right parenthesis space equals space straight x cubed cos cubed straight x space equals space minus straight f left parenthesis straight x right parenthesis
therefore space space space straight f left parenthesis straight x right parenthesis space is space an space odd space function space of space straight x
therefore space space space space space straight I space equals space 0 space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space integral subscript negative straight a end subscript superscript straight a straight f left parenthesis straight x right parenthesis space dx space space equals space 0 space if space straight f left parenthesis straight x right parenthesis space is space an space odd space function close square brackets

    Question 176
    CBSEENMA12032586

    Evaluate integral subscript 2 superscript 3 fraction numerator square root of straight x over denominator square root of 5 minus straight x end root plus square root of straight x end fraction dx

    Solution

    Let I = integral subscript 2 superscript 3 fraction numerator square root of straight x over denominator square root of 5 minus straight x end root plus square root of straight x end fraction dx                              ...(1)
    therefore space space space space space straight I space equals space integral subscript 2 superscript 3 fraction numerator square root of 2 plus 3 minus straight x end root over denominator square root of 5 minus left parenthesis 2 plus 3 minus straight x right parenthesis plus square root of 2 plus 3 minus straight x end root end root end fraction dx
                                                          open square brackets because space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f left parenthesis straight a plus straight b minus straight x right parenthesis space dx close square brackets
    therefore space space space space space straight I space equals space integral subscript 2 superscript 3 fraction numerator square root of 5 minus straight x end root over denominator square root of straight x plus square root of 5 minus straight x end root end fraction dx                           ...(2)
    Adding (1) and (2), we get,
             2 space straight I space equals space integral subscript 2 superscript 3 fraction numerator square root of straight x plus square root of 5 minus straight x end root over denominator square root of straight x plus square root of 5 minus straight x end root end fraction dx space equals space integral subscript 2 superscript 3 1 dx space equals space open square brackets straight x close square brackets subscript 2 superscript 3 space equals space 3 space minus space 2 space space equals space 1
    therefore space space space space straight I space equals space 1 half

    Question 177
    CBSEENMA12032587

    Evaluate integral subscript 1 superscript 4 straight f left parenthesis straight x right parenthesis space dx comma space space space where space space space straight f left parenthesis straight x right parenthesis space equals space open curly brackets table attributes columnalign left end attributes row cell 4 straight x plus 3 space if space 1 space less or equal than space straight x space less or equal than space 2 end cell row cell 3 straight x plus 5 space if space 2 space less or equal than space straight x space less or equal than space 4 end cell end table close.

    Solution

    Here   straight f left parenthesis straight x right parenthesis space equals space open curly brackets table attributes columnalign left end attributes row cell 4 straight x plus 3 space if space 1 space less or equal than space straight x space less or equal than 2 end cell row cell 3 straight x plus 5 space if space 2 space less or equal than space straight x space less or equal than 4 end cell end table close
    Let    I = integral subscript 1 superscript 4 straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 1 superscript 2 straight f left parenthesis straight x right parenthesis space dx space plus space integral subscript 2 superscript 4 straight f left parenthesis straight x right parenthesis space dx
                equals space integral subscript 1 superscript 2 left parenthesis 4 straight x plus 3 right parenthesis space dx plus integral subscript 2 superscript 4 space left parenthesis 3 straight x plus 5 right parenthesis space dx space equals space open square brackets 4 straight x squared over 2 plus 3 space straight x close square brackets subscript 1 superscript 2 plus open square brackets fraction numerator 3 straight x squared over denominator 2 end fraction plus 5 straight x close square brackets subscript 2 superscript 4
equals space open square brackets left parenthesis 8 plus 6 right parenthesis space minus space left parenthesis 2 plus 3 right parenthesis close square brackets space plus space open square brackets left parenthesis 24 plus 20 right parenthesis space minus space left parenthesis 6 plus 10 right parenthesis close square brackets
equals space left parenthesis 14 minus 5 right parenthesis space plus space left parenthesis 44 minus 16 right parenthesis space equals space 9 space plus space 28 space equals space 37.

    Question 178
    CBSEENMA12032588

    Evaluate integral subscript 0 superscript straight pi over 4 end superscript space log space left parenthesis 1 plus tanx right parenthesis space dx.

    Solution

    Let I = integral subscript 0 superscript straight pi over 4 end superscript space log left parenthesis 1 plus tanx right parenthesis space dx space equals space integral subscript 0 superscript straight pi over 4 end superscript log open square brackets 1 plus tan open parentheses straight pi over 4 minus straight x close parentheses close square brackets dx
                                                                    open square brackets because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
             equals space integral subscript 0 superscript straight pi over 4 end superscript space log open square brackets 1 plus fraction numerator 1 minus tanx over denominator 1 plus tanx end fraction close square brackets dx space equals space integral subscript 0 superscript straight pi over 4 end superscript space log space open square brackets fraction numerator 1 plus tanx plus 1 minus tanx over denominator 1 plus tanx end fraction close square brackets dx
              equals space integral subscript 0 superscript straight pi over 4 end superscript log open parentheses fraction numerator 2 over denominator 1 plus tanx end fraction close parentheses dx space equals space integral subscript 0 superscript straight pi over 4 end superscript log space 2 space dx space minus space integral subscript 0 superscript straight pi over 4 end superscript log left parenthesis 1 plus tanx right parenthesis space dx
     therefore space space space straight I space equals space log space 2 integral subscript 0 superscript straight pi over 4 end superscript space 1 space dx space minus space 1                                                   open square brackets because space space of space left parenthesis 1 right parenthesis close square brackets
    rightwards double arrow space space space 2 space straight I space equals space log space 2 space open square brackets straight x close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space log space 2 open square brackets straight pi over 4 minus 0 close square brackets space space space space space space rightwards double arrow space space space 2 space straight I space equals space straight pi over 4 log 2 space rightwards double arrow space straight I space equals space straight pi over 8 log space 2
              

    Question 179
    CBSEENMA12032589

    Show that integral subscript 0 superscript straight pi over 2 end superscript space log space tanx space dx space equals space 0

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript space log space tanx space dx
     therefore space space space space space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space log space tan open parentheses straight pi over 2 minus straight x close parentheses space dx              open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis dx close square brackets
    therefore        straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript log space cotx space dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript log fraction numerator 1 over denominator tan space straight x end fraction dx space equals space integral subscript 0 superscript straight pi divided by 2 end superscript log space 1 space dx space minus space integral subscript 0 superscript straight pi divided by 2 end superscript log space tanx space dx
      = 0 -  I
    therefore space space space space 2 space straight I space equals space 0 space space space space space space space rightwards double arrow space space space space straight I space equals space 0
therefore space space space space space space integral subscript 0 superscript straight pi divided by 2 end superscript log space tanx space dx space equals space 0

    Question 180
    CBSEENMA12032590

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript 4 open vertical bar straight x minus 1 close vertical bar space dx

    Solution

    Let I = integral subscript 0 superscript 4 open vertical bar straight x minus 1 close vertical bar space dx
      For  0 less or equal than straight x less or equal than 1 comma space space straight x minus 1 less or equal than 0 space space space rightwards double arrow space space space open vertical bar straight x minus 1 close vertical bar space equals space minus left parenthesis straight x minus 1 right parenthesis
    and for 1 less or equal than straight x less or equal than 4 comma space space straight x minus 1 greater or equal than 0 space space space rightwards double arrow space space space open vertical bar straight x minus 1 close vertical bar space equals space straight x space minus 1
    therefore space space space space space space straight I space equals space integral subscript 0 superscript 1 open vertical bar straight x minus 1 close vertical bar dx plus integral subscript 1 superscript 4 open vertical bar straight x minus 1 close vertical bar dx space equals space integral subscript 0 superscript 1 minus left parenthesis straight x minus 1 right parenthesis dx plus integral subscript 1 superscript 4 left parenthesis straight x minus 1 right parenthesis space dx
                equals negative open square brackets straight x squared over 2 minus straight x close square brackets subscript 0 superscript 1 plus open square brackets straight x squared over 2 minus straight x close square brackets subscript 1 superscript 4 space equals space minus open square brackets open parentheses 1 half minus 1 close parentheses minus left parenthesis 0 minus 0 right parenthesis close square brackets space plus space open square brackets open parentheses 16 over 2 minus 4 close parentheses minus open parentheses 1 half minus 1 close parentheses close square brackets
equals space minus open parentheses 1 half close parentheses plus open parentheses 4 plus 1 half close parentheses space equals space 5

    Question 181
    CBSEENMA12032591
    Question 182
    CBSEENMA12032592

    Show that:
    integral subscript 1 superscript 5 open vertical bar straight x minus 3 close vertical bar space dx space equals space 4

    Solution

    Let I = integral subscript 1 superscript 5 open vertical bar straight x minus 3 close vertical bar space dx
    For        1 less or equal than straight x less or equal than 3 comma space space straight x minus 3 space less or equal than space 0 space space space space space space space space rightwards double arrow space space space space open vertical bar straight x minus 3 close vertical bar space equals space minus left parenthesis straight x minus 3 right parenthesis
    and for 3 less or equal than straight x less or equal than 5 comma space space space straight x minus 3 greater or equal than 0 space space space space space rightwards double arrow space space space open vertical bar straight x minus 3 close vertical bar space equals space straight x minus 3
    therefore space space space space straight I space equals space integral subscript 1 superscript 3 open vertical bar straight x minus 3 close vertical bar dx space space plus integral subscript 3 superscript 5 open vertical bar straight x minus 3 close vertical bar space dx space equals space minus integral subscript 1 superscript 3 left parenthesis straight x minus 3 right parenthesis dx space plus integral subscript 3 superscript 5 left parenthesis straight x minus 3 right parenthesis space dx
                equals negative open square brackets straight x squared over 2 minus 3 straight x close square brackets subscript 1 superscript 3 space plus space open square brackets straight x squared over 2 minus 3 straight x close square brackets subscript 3 superscript 5
equals space minus open square brackets open parentheses 9 over 2 minus 9 close parentheses space minus open parentheses 1 half minus 3 close parentheses close square brackets plus open square brackets open parentheses 25 over 2 minus 15 close parentheses minus open parentheses 9 over 2 minus 9 close parentheses close square brackets space equals space 9 over 2 minus 5 over 2 minus 5 over 2 plus 9 over 2 equals 4.

    Question 183
    CBSEENMA12032593

    Show that:
    integral subscript 0 superscript 1 open vertical bar 3 straight x minus 1 close vertical bar space dx space equals space 5 over 6

    Solution

    Let I = integral subscript 0 superscript 1 open vertical bar 3 straight x minus 1 close vertical bar space dx
    For          0 less or equal than straight x less or equal than 1 third comma space space space 3 straight x minus 1 less or equal than 0 space space space space rightwards double arrow space space space space open vertical bar 3 straight x minus 1 close vertical bar space equals space minus left parenthesis 3 straight x minus 1 right parenthesis
    and for   1 third less or equal than straight x less or equal than 1 comma space space 3 straight x minus 1 greater or equal than 0 space space space space space rightwards double arrow space space open vertical bar 3 straight x minus 1 close vertical bar space equals space 3 straight x minus 1
    therefore space space space straight I space equals space integral subscript 0 superscript 1 third end superscript open vertical bar 3 straight x minus 1 close vertical bar dx plus integral subscript 1 third end subscript superscript 1 open vertical bar 3 straight x minus 1 close vertical bar dx space equals space minus integral subscript 0 superscript 1 third end superscript left parenthesis 3 straight x minus 1 right parenthesis dx plus integral subscript 1 third end subscript superscript 1 left parenthesis 3 straight x minus 1 right parenthesis space dx
             equals negative open square brackets 3 over 2 straight x squared minus straight x close square brackets subscript 0 superscript 1 third end superscript space plus space open square brackets 3 over 2 straight x squared minus straight x close square brackets subscript 1 third end subscript superscript 1
equals negative open square brackets open parentheses 1 over 6 minus 1 third close parentheses minus 0 close square brackets space plus space open square brackets open parentheses 3 over 2 minus 1 close parentheses minus open parentheses 1 over 6 minus 1 third close parentheses close square brackets space equals space 1 over 6 plus 1 half plus 1 over 6 equals 5 over 6.

    Question 184
    CBSEENMA12032594

    By using the properties of definite integrals, evaluate the following integral:

    integral subscript negative 5 end subscript superscript 5 open vertical bar straight x plus 2 close vertical bar dx

    Solution

    LetI = integral subscript negative 5 end subscript superscript 5 open vertical bar straight x plus 2 close vertical bar dx
    For - 5 ≤ x ≤ – 2, x + 2 ≤ 0 ⇒ | x + 2 | = – (x + 2) and for – 2 ≤ x ≤ 5, x + 2 ≥ 0 ⇒ | x + 2 | = x + 2
    therefore space space space space space space straight I space equals space integral subscript 2 superscript negative 2 end superscript open vertical bar straight x plus 2 close vertical bar space dx space plus space integral subscript negative 2 end subscript superscript 5 open vertical bar straight x plus 2 close vertical bar space dx space space equals integral subscript negative 5 end subscript superscript negative 2 end superscript minus left parenthesis straight x plus 2 right parenthesis space dx plus integral subscript negative 2 end subscript superscript 5 left parenthesis straight x plus 2 right parenthesis space dx
                 equals negative integral subscript 5 superscript negative 2 end superscript left parenthesis straight x plus 2 right parenthesis space dx plus integral subscript negative 2 end subscript superscript 5 left parenthesis straight x plus 2 right parenthesis space dx space equals space minus open square brackets straight x squared over 2 plus 2 straight x close square brackets subscript negative 5 end subscript superscript negative 2 end superscript plus open square brackets straight x squared over 2 plus 2 straight x close square brackets subscript negative 2 end subscript superscript 5
equals negative open square brackets open parentheses 4 over 2 minus 4 close parentheses minus open parentheses 25 over 2 minus 10 close parentheses close square brackets space plus space open square brackets open parentheses 25 over 2 plus 10 close parentheses minus open parentheses 4 over 2 minus 4 close parentheses close square brackets
equals negative open square brackets negative 2 minus 5 over 2 close square brackets plus open square brackets 45 over 2 plus 2 close square brackets space equals space 9 over 2 plus 49 over 2 equals 58 over 2 equals space space 29

    Question 185
    CBSEENMA12032595

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 2 superscript 8 open vertical bar straight x minus 5 close vertical bar space dx

    Solution

    Let I = integral subscript 2 superscript 8 open vertical bar straight x minus 5 close vertical bar space dx
    For 2 ≤ r ≤ 5, x – 5 ≤ 0 ⇒ | x – 5 | = – (x – 5) and for 5 ≤ x ≤ 8, x – 5 ≥ 0 ⇒ | x – 5 | = x – 5
    therefore space space space space straight I space equals space integral subscript 2 superscript 5 open vertical bar straight x minus 5 close vertical bar dx space plus space integral subscript 5 superscript 8 open vertical bar straight x minus 5 close vertical bar space dx
               equals negative integral subscript 2 superscript 5 left parenthesis straight x minus 5 right parenthesis dx plus integral subscript 5 superscript 8 left parenthesis straight x minus 5 right parenthesis dx space equals space minus open square brackets straight x squared over 2 minus 5 straight x close square brackets subscript 2 superscript 5 plus open square brackets straight x squared over 2 minus 5 straight x close square brackets subscript 5 superscript 8
             equals negative open square brackets open parentheses 25 over 2 minus 25 close parentheses space minus space open parentheses 4 over 2 minus 10 close parentheses close square brackets space plus space open square brackets open parentheses 64 over 2 minus 40 close parentheses minus open parentheses 25 over 2 minus 25 close parentheses close square brackets
equals negative open square brackets negative 25 over 2 plus 8 close square brackets space plus open square brackets negative 8 plus 25 over 2 close square brackets space equals space 9 over 2 plus 9 over 2 space equals 9

    Question 186
    CBSEENMA12032596

    Show that:
    integral subscript negative 1 end subscript superscript 2 open vertical bar straight x cubed minus straight x close vertical bar space dx.


    Solution

    We have
    1 less or equal than straight x less or equal than 0 space space rightwards double arrow space straight x cubed minus straight x space equals space straight x left parenthesis straight x squared minus 1 right parenthesis space greater or equal than 0 space space rightwards double arrow space space open vertical bar straight x cubed minus straight x close vertical bar space equals space straight x cubed minus straight x
0 less or equal than straight x less or equal than 1 space space space rightwards double arrow space space straight x cubed minus straight x space equals space straight x left parenthesis straight x squared minus 1 right parenthesis less or equal than 0 space space rightwards double arrow space space open vertical bar straight x cubed minus straight x close vertical bar space equals space minus left parenthesis straight x cubed minus straight x right parenthesis
1 less or equal than straight x less or equal than 2 space space space rightwards double arrow space straight x cubed minus straight x space equals space straight x left parenthesis straight x squared minus 1 right parenthesis space greater or equal than space 0 space rightwards double arrow space space open vertical bar straight x cubed minus straight x close vertical bar space equals space straight x cubed minus straight x
    Let  straight I space equals space integral subscript negative 1 end subscript superscript 2 open vertical bar straight x cubed minus straight x close vertical bar space dx space equals space integral subscript negative 1 end subscript superscript 0 open vertical bar straight x cubed minus straight x close vertical bar space dx space space plus integral subscript 0 superscript 1 open vertical bar straight x cubed minus straight x close vertical bar space dx plus integral subscript 1 superscript 2 open vertical bar straight x cubed minus straight x close vertical bar space dx
               equals space integral subscript negative 1 end subscript superscript 0 left parenthesis straight x cubed minus straight x right parenthesis dx space minus space integral subscript 0 superscript 1 left parenthesis straight x cubed minus straight x right parenthesis space dx space plus space integral subscript 1 superscript 2 left parenthesis straight x cubed minus straight x right parenthesis space dx
                equals space open square brackets straight x to the power of 4 over 4 minus straight x squared over 2 close square brackets subscript negative 1 end subscript superscript 0 space minus open square brackets straight x to the power of 4 over 4 minus straight x squared over 2 close square brackets subscript 0 superscript 1 plus open square brackets straight x to the power of 4 over 4 minus straight x squared over 2 close square brackets subscript 1 superscript 2
equals space open square brackets left parenthesis 0 minus 0 right parenthesis minus open parentheses 1 fourth minus 1 half close parentheses close square brackets space minus open square brackets open parentheses 1 fourth minus 1 half close parentheses minus left parenthesis 0 minus 0 right parenthesis close square brackets space plus space open square brackets left parenthesis 4 minus 2 right parenthesis minus open parentheses 1 fourth minus 1 half close parentheses close square brackets
equals space minus open parentheses 1 fourth minus 1 half close parentheses minus open parentheses 1 fourth minus 1 half close parentheses plus 2 minus open parentheses 1 fourth minus 1 half close parentheses space equals space minus 3 open parentheses 1 fourth minus 1 half close parentheses plus 2
equals negative 3 open parentheses fraction numerator 1 minus 2 over denominator 4 end fraction close parentheses plus 2 space equals space minus 3 open parentheses negative 1 fourth close parentheses space plus 2 space equals space 3 over 4 plus 2 space equals space fraction numerator 3 plus 8 over denominator 4 end fraction space equals space 11 over 4

    Question 187
    CBSEENMA12032597

    Evaluate: integral subscript 0 superscript 1 open vertical bar 2 straight x minus 1 close vertical bar space dx.

    Solution

    Let straight I space equals space integral subscript 0 superscript 1 space open vertical bar 2 straight x minus 1 close vertical bar space dx
    For 0 less or equal than straight x less or equal than 1 half comma space space space 2 straight x minus 1 space less or equal than 0 space space space rightwards double arrow space space space open vertical bar 2 straight x minus 1 close vertical bar space equals space minus left parenthesis 2 straight x minus 1 right parenthesis
    and for 1 half less or equal than straight x less or equal than 1 comma space space 2 straight x minus 1 greater or equal than 0 space space space space rightwards double arrow space space space open vertical bar 2 straight x minus 1 close vertical bar space equals space 2 straight x minus 1
    therefore space space space space space straight I space equals space integral subscript 0 superscript 1 half end superscript open vertical bar 2 straight x minus 1 close vertical bar space dx plus integral subscript 1 half end subscript superscript 1 open vertical bar 2 straight x minus 1 close vertical bar space dx space equals space minus integral subscript 0 superscript 1 half end superscript left parenthesis 2 straight x minus 1 right parenthesis space dx plus integral subscript 1 half end subscript superscript 1 left parenthesis 2 straight x minus 1 right parenthesis space dx
               equals space minus open square brackets straight x squared minus straight x close square brackets subscript 0 superscript 1 half end superscript space plus space open square brackets straight x squared minus straight x close square brackets subscript 1 half end subscript superscript 1
equals negative open square brackets open parentheses 1 fourth minus 1 half close parentheses minus open parentheses 0 minus 0 close parentheses close square brackets space plus space open square brackets left parenthesis 1 minus 1 right parenthesis space minus space open parentheses 1 fourth minus 1 half close parentheses close square brackets
equals space minus open parentheses 1 fourth minus 1 half close parentheses minus open parentheses 1 fourth minus 1 half close parentheses space equals space minus 2 space open parentheses 1 fourth minus 1 half close parentheses
equals negative 2 open parentheses fraction numerator 1 minus 2 over denominator 4 end fraction close parentheses space equals negative 2 open parentheses negative 1 fourth close parentheses space equals space 1 half

    Question 188
    CBSEENMA12032598

    Show that:
    integral subscript 0 superscript straight pi open vertical bar cos space straight x close vertical bar space dx space equals 2

    Solution

    Let I = integral subscript 0 superscript straight pi open vertical bar cos space straight x close vertical bar space dx
    For 0 less or equal than straight x less or equal than straight pi over 2 space cosx space greater or equal than 0 space rightwards double arrow space space open vertical bar cos space straight x close vertical bar space equals space cos space straight x
    and for straight pi over 2 less or equal than straight x less or equal than straight pi comma space space space cos space straight x space less or equal than 0 space space rightwards double arrow space space space open vertical bar cos space straight x close vertical bar space equals space minus cos space straight x
    therefore space space space straight I space equals integral subscript 0 superscript straight pi over 2 end superscript open vertical bar cos space straight x close vertical bar dx space plus space integral subscript straight pi over 2 end subscript superscript straight pi open vertical bar cosx close vertical bar dx space equals space integral subscript 0 superscript straight pi over 2 end superscript cosx space dx space minus space integral subscript straight pi over 2 end subscript superscript straight pi cosx space dx
    equals space open square brackets sin space straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space minus space open square brackets sin space straight x close square brackets subscript straight pi over 2 end subscript superscript straight pi space equals space open parentheses sin straight pi over 2 minus sin space 0 close parentheses space minus space open square brackets sin space straight pi space minus space sin space straight pi over 2 close square brackets
equals space left parenthesis 1 minus 0 right parenthesis space minus space left parenthesis 0 minus 1 right parenthesis space equals space 2

    Question 189
    CBSEENMA12032599

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript space open vertical bar sin space straight x space cosx close vertical bar space dx space equals space 1 half


    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript open vertical bar sinx space cosx close vertical bar dx space equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript open vertical bar 2 space sinx space cosx close vertical bar dx
            equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript open vertical bar sin space 2 straight x close vertical bar dx space equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x space dx space equals space 1 half open square brackets fraction numerator negative cos space 2 straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space minus 1 fourth open square brackets cos space 2 straight x close square brackets subscript 0 superscript straight pi over 2 end superscript
            equals negative 1 fourth left square bracket cos space straight pi space minus space cos space 0 right square bracket space equals space minus 1 fourth left square bracket negative 1 minus 1 right square bracket space space equals space 1 half

    Question 190
    CBSEENMA12032600

    Show that:
    integral subscript straight pi over 4 end subscript superscript straight pi over 4 end superscript open vertical bar sin space straight x close vertical bar dx space equals space 2 minus square root of 2



    Solution

    Let I = integral subscript negative straight pi over 4 end subscript superscript straight pi over 4 end superscript space open vertical bar sin space straight x close vertical bar space dx
    For negative straight pi over 4 less or equal than straight x less or equal than 0 comma space space space open vertical bar sin space straight x close vertical bar space equals space minus sin space straight x space
    and for 0 less or equal than straight x less or equal than straight pi over 4 comma space space open vertical bar sin space straight x close vertical bar space equals space sin space straight x
    therefore space space space straight I space equals space integral subscript negative straight pi over 4 end subscript superscript 0 open vertical bar sin space straight x close vertical bar dx plus integral subscript 0 superscript straight pi over 4 end superscript open vertical bar sin space straight x close vertical bar dx space equals space minus integral subscript negative straight pi over 4 end subscript superscript 0 sinx space dx plus integral subscript 0 superscript straight pi over 4 end superscript sinx space dx
               equals space open square brackets cos space straight x close square brackets subscript negative straight pi over 4 end subscript superscript 0 space minus space open square brackets cos space straight x close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space open square brackets cos space 0 space minus space cos space open parentheses negative straight pi over 4 close parentheses close square brackets space minus space open square brackets cos space straight pi over 4 minus cos space 0 close square brackets
equals space open parentheses 1 minus fraction numerator 1 over denominator square root of 2 end fraction close parentheses space minus space open square brackets fraction numerator 1 over denominator square root of 2 end fraction minus 1 close square brackets space equals space 2 minus fraction numerator 2 over denominator square root of 2 end fraction space equals space 2 minus square root of 2
              
               

    Question 191
    CBSEENMA12032601

    Show that:
    integral subscript negative 1 end subscript superscript 3 over 2 end superscript open vertical bar straight x space sinπ space straight x close vertical bar space dx space equals space 3 over straight pi plus 1 over straight pi squared



    Solution

    We have
                    negative 1 less or equal than straight x less or equal than 0 space space space rightwards double arrow space space straight x space less or equal than space 0 comma space space sinπx less or equal than 0 space space rightwards double arrow space space straight x space sinπx space greater or equal than 0
0 space less or equal than space straight x space less or equal than space 1 space space rightwards double arrow straight x greater or equal than 0 comma space space sin space πx space greater or equal than 0 space space rightwards double arrow space straight x space sinπx greater or equal than 0
1 less or equal than straight x less or equal than 3 over 2 space rightwards double arrow space straight x greater or equal than 0 comma space space sin space straight pi space straight x space less or equal than 0 space space rightwards double arrow space straight x space sinπx space less or equal than 0
    therefore space space space open vertical bar straight x space sin space straight pi space straight x close vertical bar space equals space open curly brackets table attributes columnalign left end attributes row cell straight x space sinπx comma space space space space space minus 1 less or equal than straight x less or equal than 1 end cell row cell negative straight x space sinπx comma space space space space space 1 less or equal than straight x less or equal than 3 over 2 space space space space end cell end table close
    therefore space space space integral subscript 1 superscript 3 over 2 end superscript open vertical bar straight x space sinπ space straight x close vertical bar dx space equals space integral subscript negative 1 end subscript superscript 1 open vertical bar straight x space sinπ space straight x close vertical bar dx plus integral subscript 1 superscript 3 over 2 end superscript open vertical bar straight x space sinπx close vertical bar dx
space space space space space space space space space space space equals space integral subscript negative 1 end subscript superscript 1 space straight x space sinπ space straight x space dx space space minus integral subscript 1 superscript 3 over 2 end superscript straight x space sinπx space dx
              equals space open square brackets straight x. space fraction numerator negative cos space πx over denominator straight pi end fraction close square brackets subscript negative 1 end subscript superscript 1 space minus space integral subscript negative 1 end subscript superscript 1 1. space fraction numerator negative cosπx over denominator straight pi end fraction dx minus open square brackets straight x fraction numerator negative cosπ space straight x over denominator straight pi end fraction close square brackets subscript 1 superscript 3 over 2 end superscript plus integral subscript 1 superscript 3 over 2 end superscript 1. fraction numerator negative cos space πx over denominator straight pi end fraction dx
               equals space 1 over straight pi left square bracket straight x space cos space straight pi space straight x right square bracket subscript negative 1 end subscript superscript 1 space plus space 1 over straight pi squared left square bracket sin space straight pi space straight x right square bracket subscript negative 1 end subscript superscript 1 plus 1 over straight pi left square bracket straight x space cosπ space straight x right square bracket subscript 1 superscript 3 over 2 end superscript minus 1 over straight pi squared left square bracket sin space straight pi space straight x right square bracket subscript 1 superscript 3 over 2 end superscript
equals space minus 1 over straight pi left square bracket cosπ space plus space cosπ right square bracket space plus space 1 over straight pi squared left square bracket sin space straight pi space plus space sin space straight pi right square bracket
                                                                plus 1 over straight pi open square brackets 3 over 2 cos fraction numerator 3 straight pi over denominator 2 end fraction minus cosπ close square brackets minus 1 over straight pi squared open square brackets sin space fraction numerator 3 straight pi over denominator 2 end fraction minus sin space straight pi close square brackets
               equals negative 1 over straight pi left square bracket negative 1 minus 1 right square bracket space plus space 1 over straight pi squared left square bracket 0 plus 0 right square bracket space plus 1 over straight pi left square bracket negative 1 minus 0 right square bracket space equals space 2 over straight pi plus 0 plus 1 over straight pi plus 1 over straight pi squared
                equals space 3 over straight pi plus 1 over straight pi squared

    Question 192
    CBSEENMA12032602

    Show that:
    integral subscript 0 superscript 2 straight x square root of 2 minus straight x end root space equals fraction numerator 16 square root of 2 over denominator 15 end fraction

    Solution

    Let I = integral subscript 0 superscript 2 straight x square root of 2 minus straight x end root dx
            equals space integral subscript 0 superscript 2 left parenthesis 2 minus straight x right parenthesis space square root of 2 minus left parenthesis 2 minus straight x right parenthesis space dx end root           open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
       equals space integral subscript 0 superscript 2 left parenthesis 2 minus straight x right parenthesis space square root of straight x dx space equals integral subscript 0 superscript 2 open parentheses 2 straight x to the power of 1 half end exponent minus straight x to the power of 3 over 2 end exponent close parentheses dx space equals space open square brackets 2 space fraction numerator straight x to the power of begin display style 3 over 2 end style end exponent over denominator begin display style 3 over 2 end style end fraction minus fraction numerator straight x to the power of begin display style 5 over 2 end style end exponent over denominator begin display style 5 over 2 end style end fraction close square brackets subscript 0 superscript 2 space equals space open square brackets 4 over 3 straight x to the power of 3 over 2 end exponent minus 2 over 5 straight x to the power of 5 over 2 end exponent close square brackets subscript 0 superscript 2
equals space open parentheses 4 over 3 2 to the power of 3 over 2 end exponent minus 2 over 5 2 to the power of 5 over 2 end exponent close parentheses minus left parenthesis 0 minus 0 right parenthesis space equals 4 over 3 cross times 2 square root of 2 minus 2 over 5 cross times 4 square root of 2 space equals 8 over 3 square root of 2 minus 8 over 5 square root of 2
equals space fraction numerator 40 square root of 2 minus 24 square root of 2 over denominator 15 end fraction space equals space fraction numerator 16 square root of 2 over denominator 15 end fraction

    Question 193
    CBSEENMA12032603

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript 1 space straight x space left parenthesis 1 minus straight x right parenthesis to the power of straight n space dx

    Solution

    Let I = integral subscript 0 superscript 1 straight x left parenthesis 1 minus straight x right parenthesis to the power of straight n space dx space equals space integral subscript 0 superscript 1 left parenthesis 1 minus straight x right parenthesis space open curly brackets 1 minus left parenthesis 1 minus straight x right parenthesis close curly brackets to the power of straight n space dx
                                                                                      open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
             equals space integral subscript 0 superscript 1 left parenthesis 1 minus straight x right parenthesis. space space straight x to the power of straight n space dx space equals space integral subscript 0 superscript 1 left parenthesis straight x to the power of straight n minus straight x to the power of straight n plus 1 end exponent right parenthesis space dx space equals space open square brackets fraction numerator straight x to the power of straight n plus 1 end exponent over denominator straight n plus 1 end fraction minus fraction numerator straight x to the power of straight n plus 2 end exponent over denominator straight n plus 2 end fraction close square brackets subscript 0 superscript 1
equals space open parentheses fraction numerator 1 over denominator straight n plus 1 end fraction minus fraction numerator 1 over denominator straight n plus 2 end fraction close parentheses space minus space left parenthesis 0 minus 0 right parenthesis space equals space fraction numerator 1 over denominator straight n plus 1 end fraction minus fraction numerator 1 over denominator straight n plus 2 end fraction
equals space fraction numerator straight n plus 2 minus straight n minus 1 over denominator left parenthesis straight n plus 1 right parenthesis thin space left parenthesis straight n plus 2 right parenthesis end fraction space equals space fraction numerator 1 over denominator left parenthesis straight n plus 1 right parenthesis thin space left parenthesis straight n plus 2 right parenthesis end fraction

    Question 194
    CBSEENMA12032604

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx minus cosx over denominator 1 plus sinxcosx end fraction dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx minus cosx over denominator 1 plus sinx. cosx end fraction dx                                    ...(1)
    therefore space space space space space space space straight I space space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin space open parentheses begin display style straight pi over 2 end style minus straight x close parentheses minus cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator 1 plus sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses space cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction      open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets

    rightwards double arrow space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cosx minus space sinx over denominator 1 plus cosx space sinx end fraction dx space space space rightwards double arrow space space straight I space equals space minus integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx minus cosx over denominator 1 plus sinx space cosx end fraction dx
rightwards double arrow space space straight I space equals space minus straight I space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space of space left parenthesis 1 right parenthesis close square brackets
rightwards double arrow space 2 space straight I space equals space 0 space rightwards double arrow space straight I space equals space 0

    Question 195
    CBSEENMA12032605

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript 2 straight x space log space tanx space dx space equals space 0

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x space log space tanx space dx
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript sin space 2 open parentheses straight pi over 2 minus straight x close parentheses. space log space tan open parentheses straight pi over 2 minus straight x close parentheses dx space space space rightwards double arrow space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x space log space cot space straight x space dx
    rightwards double arrow space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space sin space 2 straight x space log open parentheses 1 over tanx close parentheses dx space space rightwards double arrow space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x left parenthesis log space 1 space minus space log space tanx right parenthesis space dx
rightwards double arrow space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x left parenthesis 0 minus log space tanx right parenthesis space dx space rightwards double arrow space space straight I space equals space minus integral subscript 0 superscript straight pi over 2 end superscript sin space 2 straight x space log space tanx space dx
    rightwards double arrow space space space straight I equals space minus straight I                                                              open square brackets because space space of space left parenthesis 1 right parenthesis close square brackets
    rightwards double arrow space space space space 2 space straight I space equals space 0 space space space rightwards double arrow space space space straight I space equals space 0

    Question 196
    CBSEENMA12032606

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript straight pi over 2 end superscript left parenthesis 2 space log space sinx space minus space log space sin space 2 straight x right parenthesis space dx

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript left parenthesis 2 space log space sinx space minus space log space sin space 2 straight x right parenthesis space dx               ...(1)
    therefore space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open square brackets 2 space log space sin open parentheses straight pi over 2 minus straight x close parentheses minus log space sin 2 open parentheses straight pi over 2 minus straight x close parentheses close square brackets dx        open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space left parenthesis 2 space log space cos space straight x space minus space log space sin space 2 straight x right parenthesis space dx          ...(2)
    Adding (1) and (2), we get,
        2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open square brackets 2 left parenthesis log space sinx space plus space log space cosx right parenthesis space minus space 2 space log space sin space 2 straight x close square brackets dx
              equals space integral subscript 0 superscript straight pi over 2 end superscript open square brackets 2 space log space open parentheses fraction numerator 2 space sinx space cosx over denominator 2 end fraction close parentheses minus 2 space log space sin 2 straight x close square brackets dx space equals space integral subscript 0 superscript straight pi over 2 end superscript open square brackets 2 space log space fraction numerator sin 2 straight x over denominator 2 end fraction minus 2 space log space sin 2 straight x close square brackets dx
equals space integral subscript 0 superscript straight pi over 2 end superscript left parenthesis 2 space log space sin 2 straight x minus space 2 space log space 2 space minus 2 space log space sin space 2 straight x right square bracket space dx
equals space minus space 2 space log space 2 space integral subscript 0 superscript straight pi over 2 end superscript 1 space dx space equals space minus 2 space log space 2 open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space minus 2 space log space 2 open square brackets straight pi over 2 minus 0 close square brackets space equals space minus straight pi space log space 2
therefore space 2 space straight I space equals space minus straight pi space space log space 2 space rightwards double arrow space space space straight I space equals space minus straight pi over 2 log space 2

    Question 197
    CBSEENMA12032607

    Show that:
    integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx space plus space cosx end fraction dx space equals space straight pi squared over 4

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator straight x space tan space straight x over denominator sec space straight x plus cos space straight x end fraction dx
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space tan left parenthesis straight pi minus straight x right parenthesis over denominator sec left parenthesis straight pi minus straight x right parenthesis plus cos left parenthesis straight pi minus straight x right parenthesis end fraction dx     open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
                equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space left parenthesis negative tanx right parenthesis over denominator negative secx minus cosx end fraction dx space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space tanx over denominator secx plus cosx end fraction dx
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator straight pi space tanx over denominator sec space straight x space plus space cos space straight x end fraction dx minus integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx space plus space tanx end fraction dx
    Adding (1) and (2), we get
              2 space straight I space equals integral subscript 0 superscript straight pi fraction numerator straight pi space tanx over denominator secx plus cosx end fraction dx space equals space straight pi integral subscript 0 superscript straight pi fraction numerator tanx over denominator secx plus cosx end fraction dx space equals straight pi integral subscript 0 superscript straight pi fraction numerator begin display style sinx over cosx end style over denominator begin display style 1 over cosx end style plus cosx end fraction dx
    therefore space space space space space space space space 2 straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator sinxdx over denominator 1 plus cos squared straight x end fraction
    Put cos x = t, ∴ – sin x dx = dt, or sin x dx = – dt When x = 0, t = cos 0 = 1 When x = straight pi, t = cos straight pi = – 1
    therefore space space 2 space straight I space equals space minus straight pi integral subscript 1 superscript negative 1 end superscript fraction numerator dt over denominator 1 plus straight t squared end fraction space equals space straight pi integral subscript negative 1 end subscript superscript 1 fraction numerator dt over denominator 1 plus straight t squared end fraction space equals straight pi open square brackets tan to the power of negative 1 end exponent close square brackets subscript negative 1 end subscript superscript 1 space equals straight pi open square brackets tan to the power of negative 1 end exponent left parenthesis 1 right parenthesis space minus tan to the power of negative 1 end exponent left parenthesis negative 1 right parenthesis close square brackets
space space space space space space space space space space space equals space straight pi open square brackets straight pi over 4 minus open parentheses negative straight pi over 4 close parentheses close square brackets space equals straight pi cross times straight pi over 2
    therefore space space space 2 space straight I space equals space straight pi squared over 2 space space                               rightwards double arrow space space space straight I space equals space straight pi over 4

    Question 198
    CBSEENMA12032608

    Show that:
    integral subscript 0 superscript infinity log space open parentheses straight x plus 1 over straight x close parentheses. space fraction numerator dx over denominator 1 plus straight x squared end fraction space equals space straight pi space log space 2

    Solution

    Let I = integral subscript 0 superscript infinity log space open parentheses straight x plus 1 over straight x close parentheses fraction numerator dx over denominator 1 plus straight x squared end fraction
    Put x = tan θ so that dx = sec2 θ dθ
    When straight x equals 0 comma space space straight theta space equals space 0 comma space space space When space straight x rightwards arrow space infinity comma space space space straight theta rightwards arrow space straight pi over 2
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript log open parentheses tanθ plus 1 over tanθ close parentheses fraction numerator sec squared straight theta over denominator 1 plus tan squared straight theta end fraction dθ
               
    equals space integral subscript 0 superscript straight pi over 2 end superscript log space open parentheses fraction numerator sin squared straight theta plus cos squared straight theta over denominator sinθ space cosθ end fraction close parentheses dθ space equals space integral subscript 0 superscript straight pi over 2 end superscript log space open parentheses fraction numerator 1 over denominator sin space straight theta space cosθ end fraction close parentheses dθ
equals negative integral subscript 0 superscript straight pi over 2 end superscript log space sinθ space dθ space minus space integral subscript 0 superscript straight pi over 2 end superscript log space cos space straight theta space dθ space equals space minus open parentheses negative straight pi over 2 log space 2 close parentheses space minus open parentheses negative straight pi over 2 log space 2 close parentheses
equals straight pi over 2 log space 2 space plus straight pi over 2 log space 2 space equals space straight pi space log space 2

    Question 199
    CBSEENMA12032609

    Show that:
    integral subscript 0 superscript 1 fraction numerator log space left parenthesis 1 plus straight x right parenthesis over denominator 1 plus straight x squared end fraction space equals space straight pi over 8 space log space 2

    Solution

    Let I = integral subscript 0 superscript 1 fraction numerator log left parenthesis 1 plus straight x right parenthesis over denominator 1 plus straight x squared end fraction dx
    Put x = tan θ,    ∴ dx = sec2 θ dθ
    When x = 0, tan θ = 0 ⇒ θ = 0
    When x = 1,  tan space straight theta space equals space 1 space space space space space space space space rightwards double arrow space space space space straight theta space equals space straight pi over 4

    therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 4 end superscript space log left parenthesis 1 plus tanθ right parenthesis space dθ space                                         ...(1)
               equals space integral subscript 0 superscript straight pi over 4 end superscript log space open square brackets 1 plus tan open parentheses straight pi over 4 minus straight theta close parentheses close square brackets space dθ   open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
               equals space integral subscript 0 superscript straight pi over 4 end superscript log open square brackets 1 plus fraction numerator 1 minus tanθ over denominator 1 plus tanθ end fraction close square brackets dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript log open square brackets fraction numerator 1 plus tanθ plus 1 minus tanθ over denominator 1 plus tanθ end fraction close square brackets dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript log open parentheses fraction numerator 2 over denominator 1 plus tanθ end fraction close parentheses dθ
     equals space integral subscript 0 superscript straight pi over 4 end superscript log space 2 space dθ space space minus integral subscript 0 superscript straight pi over 4 end superscript log left parenthesis 1 plus tanθ right parenthesis space dθ
    therefore space space space space straight I space equals space log space 2 integral subscript 0 superscript straight pi over 4 end superscript space 1. space dθ space minus space 1                                                          [because of (1)]
    rightwards double arrow space 2 space straight I space space equals space log space 2 open square brackets straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space open parentheses straight pi over 4 minus 0 close parentheses space log space 2 space rightwards double arrow space space 2 space straight I space equals space straight pi over 4 log 2 space space rightwards double arrow space space straight I equals straight pi over 8 log space 2

    Question 200
    CBSEENMA12032610

    Evaluate:
    integral subscript 0 superscript straight pi fraction numerator straight x space over denominator 1 plus sinx end fraction dx space equals space straight pi

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator straight x over denominator 1 plus sinx end fraction dx                     ...(1)
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator straight pi minus straight x over denominator 1 plus sin left parenthesis straight pi minus straight x right parenthesis end fraction dx space space space space space space space space space space space space space space space space space space space space space space rightwards double arrow space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator straight pi minus straight x over denominator 1 plus sinx end fraction dx
    rightwards double arrow space space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sinx end fraction dx minus integral subscript 0 superscript straight pi fraction numerator straight x over denominator 1 plus sinx end fraction dx
    rightwards double arrow space space space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sinx end fraction dx minus 1                                   open square brackets because space of space left parenthesis 1 right parenthesis close square brackets
    rightwards double arrow space space space space 2 space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sinx end fraction dx space equals straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sinx end fraction cross times fraction numerator 1 minus sinx over denominator 1 minus sinx end fraction dx
                    equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 minus sinx over denominator 1 minus sin squared straight x end fraction dx space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 minus sinx over denominator cos squared straight x end fraction dx
                     equals space straight pi integral subscript 0 superscript straight pi open parentheses fraction numerator 1 over denominator cos squared straight x end fraction minus fraction numerator sinx over denominator cos squared straight x end fraction close parentheses dx space equals space straight pi integral subscript 0 superscript straight pi open parentheses sec squared straight x minus 1 over cosx. sinx over cosx close parentheses dx
                   equals space straight pi integral subscript 0 superscript straight pi left parenthesis sec squared straight x minus secx space tanx right parenthesis space dx space equals space straight pi space left square bracket tan space straight x space minus space sec space straight x right square bracket subscript 0 superscript straight pi
                    equals space straight pi left square bracket left parenthesis tan space straight pi space minus secπ right parenthesis space minus left parenthesis tan space 0 minus space sec space 0 right parenthesis right square bracket
equals space straight pi left square bracket 0 minus left parenthesis negative 1 right parenthesis minus 0 plus 1 right square bracket space equals space straight pi left parenthesis 2 right parenthesis space equals space 2 straight pi
    therefore space space 2 space straight I space equals space 2 space straight pi space space space rightwards double arrow space space space space straight I space equals space straight pi

    Question 201
    CBSEENMA12032616

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator straight x space dx over denominator sinx space plus space cosx end fraction space equals space fraction numerator straight pi over denominator 2 square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator xdx over denominator sinx plus cosx end fraction               ...(1)
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator begin display style straight pi over 2 end style minus straight x over denominator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space space space space space space open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
              equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator begin display style straight pi over 2 minus straight x end style over denominator cosx plus sinx end fraction dx space equals space straight pi over 2 integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator cosx plus sinx end fraction space minus space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator xdx over denominator cosx plus sinx end fraction
    therefore space space space straight I space equals space space straight pi over 2 integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator cosx plus sinx end fraction space minus 1                           [because space space of space left parenthesis 1 right parenthesis]
    therefore space space space space 2 space straight I space equals space straight pi over 2 integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator cosx plus sinx end fraction dx                                             ...(2)
    Let straight I subscript 1 space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator cosx plus sinx end fraction dx           
    Put tan straight x over 2 space equals space straight t space space or space space straight x over 2 space equals space tan to the power of 1 straight t space space or space space straight x space equals space 2 space tan to the power of 1 straight t space space space space rightwards double arrow space space space space space dx space space equals fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
            sinx space equals space fraction numerator 2 space tan begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals fraction numerator 2 space straight t over denominator 1 plus straight t squared end fraction space and space cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction space
                    When x = 0, t = tan 0 = 0
    When  straight x space equals space straight pi over 2 comma space space straight t space equals space tan straight pi over 4 space equals space 1
    therefore space space space space space space straight I subscript 1 space equals space integral subscript 0 superscript 1 fraction numerator begin display style fraction numerator 1 over denominator 1 plus straight t squared end fraction end style dt over denominator begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style plus begin display style fraction numerator 2 space straight t over denominator 1 plus straight t squared end fraction end style end fraction space equals space 2 integral subscript 0 superscript 1 fraction numerator dt over denominator 1 minus straight t squared plus 2 straight t end fraction space equals space 2 integral subscript 0 superscript 1 fraction numerator dt over denominator 2 minus left parenthesis straight t squared minus 2 straight t plus 1 right parenthesis end fraction
                 equals space 2 integral subscript 0 superscript 1 fraction numerator dt over denominator left parenthesis square root of 2 right parenthesis squared minus left parenthesis straight t minus 1 right parenthesis squared end fraction space equals 2 cross times fraction numerator 1 over denominator 2 square root of 2 end fraction open square brackets log space open vertical bar fraction numerator square root of 2 plus left parenthesis straight t minus 1 right parenthesis over denominator square root of 2 minus left parenthesis straight t minus 1 right parenthesis end fraction close vertical bar close square brackets subscript 0 superscript 1
equals space fraction numerator 1 over denominator square root of 2 end fraction open square brackets log space fraction numerator square root of 2 over denominator square root of 2 end fraction minus log fraction numerator square root of 2 minus 1 over denominator square root of 2 plus 1 end fraction close square brackets space equals space minus fraction numerator 1 over denominator square root of 2 end fraction log fraction numerator square root of 2 minus 1 over denominator square root of 2 plus 1 end fraction
equals space fraction numerator 1 over denominator square root of 2 end fraction log fraction numerator square root of 2 plus 1 over denominator square root of 2 minus 1 end fraction equals fraction numerator 1 over denominator square root of 2 end fraction log open parentheses fraction numerator square root of 2 plus 1 over denominator square root of 2 minus 1 end fraction cross times fraction numerator square root of 2 plus 1 over denominator square root of 2 plus 1 end fraction close parentheses
equals space fraction numerator 1 over denominator square root of 2 end fraction log open square brackets fraction numerator left parenthesis square root of 2 plus 1 right parenthesis squared over denominator 2 minus 1 end fraction close square brackets space equals space fraction numerator 1 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis squared space equals space fraction numerator 2 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis
    therefore space space space space space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator cosx plus sinx end fraction space equals space fraction numerator 2 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis
therefore space space space space space space space equals space fraction numerator straight pi over denominator 2 square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis        

    Question 202
    CBSEENMA12032618

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin squared straight x over denominator sin space straight x space plus space cos space straight x end fraction space equals space fraction numerator 1 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin squared straight x over denominator sinx plus cosx end fraction dx                          ...(1)
    therefore space space space space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space fraction numerator sin squared open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos squared straight x over denominator cosx plus sinx end fraction dx  ...(2)
    Adding (1) and (2), we get,
                2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript open square brackets fraction numerator sin squared straight x over denominator sinx plus cosx end fraction plus fraction numerator cos squared straight x over denominator sinx plus cosx end fraction close square brackets dx space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sin squared plus cos squared straight x over denominator sinx plus cosx end fraction dx
    therefore space space space space space space space space space space space space space space 2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator sinx plus cosx end fraction dx space space space space space space space space space space space space space space space space space space space space... left parenthesis 3 right parenthesis
    Let straight I subscript 1 space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator cosx plus sinx end fraction dx
    Put tan straight x over 2 space equals space straight t space space space space or space space straight x over 2 space equals space tan to the power of negative 1 end exponent straight t space space space or space space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space space space space space space rightwards double arrow space space dx equals fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    sinx space equals space fraction numerator 2 tan begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction space space and space cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
    When x = 0,  t = tan 0 = 0
    When straight x space equals space straight pi over 2 comma space space space straight t space equals space tan straight pi over 4 space equals space 1
    therefore space space space straight I subscript 1 space equals space integral subscript 0 superscript 1 fraction numerator begin display style fraction numerator 1 over denominator 1 plus straight t squared end fraction end style dt over denominator begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style plus begin display style fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction end style end fraction space equals space 2 integral subscript 0 superscript 1 fraction numerator dt over denominator 1 minus straight t squared plus 2 straight t end fraction space equals space 2 integral subscript 0 superscript 1 fraction numerator dt over denominator 2 minus left parenthesis straight t squared minus 2 straight t right parenthesis end fraction space equals 2 integral subscript 0 superscript 1 fraction numerator dt over denominator 2 minus left parenthesis straight t squared minus 2 straight t plus 1 right parenthesis end fraction
               
    therefore space space space space space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator cosx plus sinx end fraction space equals space fraction numerator 2 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis
therefore space space space space from space left parenthesis 3 right parenthesis comma space space 2 space straight I space equals space fraction numerator 2 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis
therefore space space straight I space equals space fraction numerator 1 over denominator square root of 2 end fraction log left parenthesis square root of 2 plus 1 right parenthesis

    Question 203
    CBSEENMA12032621

    Show that:
    integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx space cosecx end fraction space equals space straight pi squared over 4


    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator straight x space tanx over denominator secx space cosecx end fraction dx                                      ...(1)
    therefore space space space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator left parenthesis straight pi minus straight x right parenthesis space tan left parenthesis straight pi minus straight x right parenthesis over denominator sec left parenthesis straight pi minus straight x right parenthesis space cosec left parenthesis straight pi minus straight x right parenthesis end fraction dx     open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space space space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator left parenthesis straight pi minus straight x right parenthesis space left parenthesis negative tan space straight x right parenthesis over denominator left parenthesis negative sec space straight x right parenthesis space cosecx end fraction dx
              straight I space equals straight pi integral subscript 0 superscript straight pi fraction numerator tan space straight x over denominator sec space straight x space cosec space straight x end fraction dx space space minus space integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator sec space straight x space cosec space straight x end fraction dx
    rightwards double arrow space space space space straight I space equals space straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator begin display style sinx over cosx end style over denominator begin display style 1 over cosx end style. begin display style 1 over sinx end style end fraction dx minus 1                           open square brackets because space of space left parenthesis 1 right parenthesis close square brackets
    rightwards double arrow space space space space 2 space straight I space equals space straight pi integral subscript 0 superscript straight pi over 2 end superscript sin squared space xdx space equals space straight pi over 2 integral subscript 0 superscript straight pi over 2 end superscript 2 space sin squared straight x space dx
rightwards double arrow space space space space 2 space straight I space equals space straight pi over 2 integral subscript 0 superscript straight pi left parenthesis 1 minus cos space 2 straight x right parenthesis space dx space equals space straight pi over 2 open square brackets straight x minus fraction numerator sin space 2 straight x over denominator 2 end fraction close square brackets subscript 0 superscript straight pi
therefore space space space space space 2 space straight I space equals space straight pi over 2 open square brackets open parentheses straight pi minus 1 half sin space 2 straight pi close parentheses space minus space open parentheses 0 minus 1 half sin space 0 close parentheses close square brackets
therefore space space space 2 space straight I space equals space straight pi over 2 open square brackets open parentheses straight pi over 2 minus 1 half cross times 0 close parentheses space minus space left parenthesis 0 minus 0 right parenthesis close square brackets space space space space rightwards double arrow space space space 2 space straight I space equals space straight pi squared over 2 space space rightwards double arrow space space straight I space equals straight pi squared over 4
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator left parenthesis straight pi minus straight x right parenthesis space left parenthesis negative tan space straight x right parenthesis over denominator left parenthesis negative sec space straight x right parenthesis space cosecx end fraction dx

    Question 204
    CBSEENMA12032627

    Show that:
    integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx plus tanx end fraction dx space equals space straight pi open parentheses straight pi over 2 minus 1 close parentheses

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx plus tanx end fraction dx                             ...(1)
    therefore space space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space tan left parenthesis straight pi minus straight x right parenthesis over denominator sec left parenthesis straight pi minus straight x right parenthesis plus tan left parenthesis straight pi minus straight x right parenthesis end fraction dx space space space space open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi open square brackets fraction numerator left parenthesis straight pi minus straight x right parenthesis space left parenthesis negative tanx right parenthesis over denominator negative secx minus tanx end fraction close square brackets dx space space space rightwards double arrow space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space tanx over denominator secx plus tanx end fraction dx
    rightwards double arrow space space space space space straight I space equals straight pi integral subscript 0 superscript straight pi fraction numerator tanx over denominator secx plus tanx end fraction dx space minus space integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx plus tanx end fraction dx
    rightwards double arrow space space straight I space equals space straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator tan space straight x over denominator secx plus tanx end fraction cross times fraction numerator secx minus tanx over denominator secx minus tanx end fraction dx space minus space 1                [because space of space left parenthesis 1 right parenthesis]
     rightwards double arrow space space space space 2 space straight I space equals space straight pi space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator tanx space secx minus tan squared straight x over denominator sec squared straight x minus tan squared straight x end fraction dx space space space rightwards double arrow space space space 2 space straight I space space equals space straight pi integral subscript 0 superscript straight pi fraction numerator secx space tanx minus left parenthesis sec squared straight x minus 1 right parenthesis over denominator 1 end fraction dx
rightwards double arrow space space space 2 straight I space equals space straight pi integral subscript 0 superscript straight pi left parenthesis secx space tanx space minus sec squared straight x plus 1 right parenthesis space dx space equals space straight pi left square bracket secx minus tanx plus straight x right square bracket subscript 0 superscript straight pi
                   equals space straight pi open square brackets secπ minus tanπ plus straight pi right parenthesis space minus space left parenthesis sec space 0 space minus tan space 0 space plus 0 right parenthesis close square brackets
equals straight pi open square brackets left parenthesis negative 1 minus 0 plus straight pi right parenthesis space minus space left parenthesis 1 minus 0 plus 0 right parenthesis close square brackets
    rightwards double arrow space space 2 space straight I space equals space straight pi left parenthesis straight pi minus 2 right parenthesis
rightwards double arrow space space space space space straight I space equals space straight pi open parentheses straight pi over 2 minus 1 close parentheses

    Question 205
    CBSEENMA12032629

    Show that:
    integral subscript 0 superscript 1 log space open parentheses 1 over straight x minus 1 close parentheses dx space equals space 0

    Solution

    Let I = integral subscript 0 superscript 1 log space open parentheses 1 over straight x minus 1 close parentheses dx
    Put x = cos2 θ, θ dx = 2 cos θ (– sin θ) dθ = – 2 sin θ cos θ dθ = – sin 2θ dθ
    When x = 0,  cos squared straight theta space equals space 0 space rightwards double arrow space space space straight theta space equals space straight pi over 2
    When x = 1, cos2 θ = 1 ⇒ θ = 0
    therefore space space space straight I space equals space minus integral subscript straight pi over 2 end subscript superscript 0 log open parentheses fraction numerator 1 over denominator cos squared straight theta end fraction minus 1 close parentheses space sin space 2 straight theta space dθ space equals space integral subscript 0 superscript straight pi over 2 end superscript log space open parentheses fraction numerator 1 minus cos squared straight theta over denominator cos squared straight theta end fraction close parentheses space sin space 2 straight theta space dθ
                                                                                            open square brackets because space space space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space minus integral subscript straight b superscript straight a straight f left parenthesis straight x right parenthesis space dx close square brackets
                    equals space integral subscript 0 superscript straight pi over 2 end superscript log open parentheses fraction numerator sin squared straight theta over denominator cos squared straight theta end fraction close parentheses. space sin space 2 straight theta space dθ
equals space integral subscript 0 superscript straight pi over 2 end superscript space log space tan squared straight theta. space space sin space 2 straight theta space dθ space equals space 2 integral subscript 0 superscript straight pi over 2 end superscript log space tanθ. space sin space 2 straight theta space dθ
                      equals 2 integral subscript 0 superscript straight pi over 2 end superscript log space tan open parentheses straight pi over 2 minus straight theta close parentheses space sin space 2 space open parentheses straight pi over 2 minus straight theta close parentheses space dθ space space space space space open square brackets space because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
                    equals 2 integral subscript 0 superscript straight pi over 2 end superscript space log space cotθ. space sin space 2 straight theta space dθ space equals space 2 integral subscript 0 superscript straight pi over 2 end superscript log open parentheses fraction numerator 1 over denominator tan space straight theta end fraction close parentheses. space sin space 2 straight theta space dθ
space equals space 2 integral subscript 0 superscript straight pi over 2 end superscript left parenthesis log space 1 space minus space log space tanθ right parenthesis space. space sin space 2 straight theta space dθ
    rightwards double arrow space space space space straight I space equals space minus 2 space integral subscript 0 superscript straight pi over 2 end superscript log space tanθ comma space sin space 2 straight theta space dθ
    therefore space space space space space space straight I space equals space minus 1 comma space space space space space space space space space space rightwards double arrow space space space space 2 space space straight I space equals space space 0 space space space space space space space space space space rightwards double arrow space space space straight I space space equals space 0
                      

    Question 206
    CBSEENMA12032630

    By using the properties of definite integrals, evaluate the following integral:
    integral subscript 0 superscript straight pi fraction numerator dx over denominator 1 plus sinx end fraction space equals space 2


    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator dx over denominator 1 plus sinx end fraction space equals space integral subscript 0 superscript straight pi fraction numerator dx over denominator 1 plus sinx end fraction cross times fraction numerator 1 minus sinx over denominator 1 minus sinx end fraction dx space equals space straight x integral subscript 0 superscript straight pi fraction numerator 1 minus sinx over denominator 1 minus sin squared straight x end fraction dx
            equals space integral subscript 0 superscript straight pi fraction numerator 1 minus sinx over denominator cos squared straight x end fraction dx space equals space integral subscript 0 superscript straight pi open parentheses fraction numerator 1 over denominator cos squared straight x end fraction minus fraction numerator sinx over denominator cos squared straight x end fraction close parentheses dx space equals space integral subscript 0 superscript straight pi open parentheses fraction numerator 1 over denominator cos squared straight x end fraction minus 1 over cosx. sinx over cosx close parentheses dx
             space equals space integral subscript 0 superscript straight pi left parenthesis sec squared straight x minus secx space tanx right parenthesis space dx space equals space open square brackets tanx space minus secx close square brackets subscript 0 superscript straight pi
space equals space open square brackets left parenthesis tanπ minus secπ right parenthesis space minus space left parenthesis tan space 0 space minus space sec space 0 right parenthesis close square brackets
space equals space open square brackets left parenthesis 0 plus 1 right parenthesis space minus space left square bracket 0 minus 1 right parenthesis close square brackets space equals space 2
                     

    Question 207
    CBSEENMA12032632

    Show that:
    integral subscript 0 superscript straight pi space straight x space. space log space sinx space dx space equals space minus straight pi squared over 2 log space 2

    Solution

    Let I = integral subscript 0 superscript straight pi straight x space log space sinx space dx                                           ...(1)
    therefore space space space space space space space space space straight I space equals space integral subscript 0 superscript straight pi left parenthesis straight pi minus straight x right parenthesis space log space sin left parenthesis straight pi minus straight x right parenthesis space dx                        open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    therefore      straight I space equals space integral subscript 0 superscript straight pi left parenthesis straight pi minus straight x right parenthesis space log space sinx space dx space equals space straight pi integral subscript 0 superscript straight pi log space sinx space dx space minus space integral subscript 0 superscript straight pi straight x space log space sinx space dx
    therefore space space space straight I space equals space straight pi integral subscript 0 superscript straight pi log space sinx space dx space minus space 1                                      open square brackets because space space of space left parenthesis 1 right parenthesis close square brackets
    therefore space space space space space 2 space space straight I space equals space straight pi space space integral subscript 0 superscript straight pi log space sinx space dx space equals space straight pi. space 2 space integral subscript 0 superscript straight pi over 2 end superscript log space sinx space dx
    therefore space space space space 2 straight I space equals space 2 straight pi open parentheses negative straight pi over 2 log space 2 close parentheses                    open square brackets because space space integral subscript 0 superscript straight pi over 2 end superscript log space sinx space dx space equals negative straight pi over 2 log space 2 close square brackets
    therefore space space space straight I equals space minus straight pi squared over 2 log space 2

    Question 208
    CBSEENMA12032633

    Show that:
    integral subscript 0 superscript straight pi over 2 end superscript open parentheses fraction numerator straight theta over denominator sin space straight theta end fraction close parentheses squared space dθ space equals space straight pi space log space 2

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript open parentheses fraction numerator straight theta over denominator sin space straight theta end fraction close parentheses squared space dθ space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator straight theta squared over denominator sin squared space straight theta end fraction dθ space equals space integral subscript 0 superscript straight pi over 2 end superscript straight theta squared space cosec squared straight theta space dθ
            equals space open square brackets straight theta squared left parenthesis negative cot space straight theta right parenthesis close square brackets subscript 0 superscript straight pi over 2 end superscript space minus space integral subscript 0 superscript straight pi over 2 end superscript 2 space straight theta. space left parenthesis negative cot space straight theta right parenthesis space dθ space equals space open square brackets straight theta squared space left parenthesis negative cot space straight theta right parenthesis close square brackets subscript 0 superscript straight pi over 2 end superscript plus 2 integral subscript 0 superscript straight pi over 2 end superscript straight theta. space cot space straight theta space dθ
space equals space open parentheses negative straight pi squared over 4 cot straight pi over 2 plus 0 close parentheses plus 2 open curly brackets open square brackets straight theta space. log space sinθ close square brackets subscript 0 superscript straight pi over 2 end superscript minus integral subscript 0 superscript straight pi over 2 end superscript 1. space log space sinθ space dθ close curly brackets
equals space straight pi squared over 4 cross times 0 plus 0 plus 2 open square brackets straight theta. space log space sinθ close square brackets subscript 0 superscript straight pi over 2 end superscript space minus space 2 integral subscript 0 superscript straight pi over 2 end superscript log space sinθ space dθ
space equals 2 open square brackets straight pi over 2 log space sin straight pi over 2 minus 0 close square brackets space minus space 2 open parentheses negative straight pi over 2 log space 2 close parentheses
space equals space 2 space left square bracket 0 minus 0 right square bracket space plus space straight pi space log space 2 space space equals space straight pi space log space 2
            

    Question 209
    CBSEENMA12032636

    Show that:
    integral subscript 0 superscript straight pi fraction numerator straight x space sinx over denominator 1 plus cos squared straight x end fraction dx space equals space straight pi squared over 4


    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator straight x space sinx over denominator 1 plus cos squared straight x end fraction dx
    therefore space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space sin left parenthesis straight pi minus straight x right parenthesis over denominator 1 plus cos squared left parenthesis straight pi minus straight x right parenthesis end fraction dx space space space space space space space space space space space space space open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
               equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space sinx over denominator 1 plus cos squared straight x end fraction dx space equals space straight pi integral subscript 0 superscript straight pi fraction numerator sinx over denominator 1 plus cos squared straight x end fraction dx minus integral subscript 0 superscript straight pi fraction numerator straight x space sinx over denominator 1 plus cos squared straight x end fraction dx
     therefore space space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator sinx over denominator 1 plus cos squared straight x end fraction dx space minus space 1
therefore space space 2 space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator sin space straight x space over denominator 1 plus cos squared straight x end fraction dx
    Put cos x = t.     ∴ sin x dx = – dt When x = 0, t = cos 0 = 1 When x = straight pi, t = cos straight pi = – 1
    therefore space space space 2 space straight I space equals space straight pi integral subscript 1 superscript negative 1 end superscript fraction numerator dt over denominator 1 plus straight t squared end fraction space equals space straight pi open square brackets tan to the power of negative 1 end exponent straight t close square brackets subscript 1 superscript negative 1 end superscript
space space space space space space space space space space space space space equals negative straight pi open square brackets tan to the power of negative 1 end exponent left parenthesis negative 1 right parenthesis space minus space tan to the power of negative 1 end exponent 1 close square brackets space equals space minus straight pi open square brackets negative straight pi over 4 minus straight pi over 4 close square brackets
therefore space space 2 space straight I space equals space straight pi squared over 2 space space rightwards double arrow space space space space straight I space equals space straight pi squared over 4
     

    Question 210
    CBSEENMA12032639

    Evaluate:
    integral subscript 0 superscript straight pi fraction numerator straight x over denominator 1 plus sin squared straight x end fraction dx.

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator straight x over denominator 1 plus sin squared straight x end fraction dx                                           ...(1)
    therefore space space space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator straight pi minus straight x over denominator 1 plus sin squared left parenthesis straight pi minus straight x right parenthesis end fraction dx space space space space space rightwards double arrow space space space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator straight pi minus straight x over denominator 1 plus sin squared straight x end fraction dx
    rightwards double arrow space space space space space space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sin squared straight x end fraction dx space space minus integral subscript 0 superscript straight pi fraction numerator straight x over denominator 1 plus sin squared straight x end fraction dx
    therefore space space space space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sin squared straight x end fraction dx minus 1 space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space space of space left parenthesis 1 right parenthesis close square brackets
    therefore space space space space space 2 space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator 1 plus sin squared straight x end fraction dx space equals space 2 straight pi space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 1 plus sin squared straight x end fraction dx
                   equals space 2 straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator sin squared straight x plus cos squared straight x plus sin squared straight x end fraction dx space equals space 2 straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator 2 sin squared straight x plus cos squared straight x end fraction dx
equals space 2 straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator begin display style fraction numerator 1 over denominator cos squared straight x end fraction end style over denominator begin display style fraction numerator 2 sin squared straight x over denominator cos squared straight x end fraction end style plus begin display style fraction numerator cos squared straight x over denominator cos squared straight x end fraction end style end fraction dx space equals space 2 straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sec squared straight x over denominator 2 space tan squared straight x plus 1 end fraction dx
    Put tan x = t, ∴ sec 2 x dx = dt When x = 0, t = tan 0 = 0
    When straight x space equals space straight pi over 2 comma space space straight t space equals space tan straight pi over 2 space rightwards arrow space space infinity
    therefore space space space space space space space space space space straight I space equals space straight pi integral subscript 0 superscript infinity fraction numerator 1 over denominator 2 straight t squared plus 1 end fraction dt space equals space straight pi over 2 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus begin display style 1 half end style end fraction dt space equals space straight pi over 2 integral subscript 0 superscript infinity fraction numerator 1 over denominator straight t squared plus open parentheses begin display style fraction numerator 1 over denominator square root of 2 end fraction end style close parentheses squared end fraction dt
                    equals space straight pi over 2 cross times fraction numerator 1 over denominator begin display style fraction numerator 1 over denominator square root of 2 end fraction end style end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight t over denominator begin display style fraction numerator 1 over denominator square root of 2 end fraction end style end fraction close parentheses close square brackets subscript 0 superscript infinity space equals space fraction numerator straight pi over denominator square root of 2 end fraction open square brackets tan to the power of negative 1 end exponent open parentheses square root of 2 straight t close parentheses close square brackets subscript 0 superscript infinity
equals space fraction numerator straight pi over denominator square root of 2 end fraction left square bracket tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 right square bracket space equals space fraction numerator straight pi over denominator square root of 2 end fraction open parentheses fraction numerator straight pi over denominator square root of 2 end fraction minus 0 close parentheses space equals space fraction numerator straight pi over denominator square root of 2 end fraction cross times straight pi over 2 space equals fraction numerator straight pi squared over denominator 2 square root of 2 end fraction

    Question 211
    CBSEENMA12032641

    By using the properties of definite integrals, evaluate the following:
    integral subscript 0 superscript straight pi log space left parenthesis 1 plus cosx right parenthesis space dx

    Solution

    Let I = integral subscript 0 superscript straight pi log left parenthesis 1 plus cosx right parenthesis space dx                                                   ...(1)
    Then I = integral subscript 0 superscript straight pi log left parenthesis 1 plus cos stack straight pi minus straight x with bar on top right parenthesis space dx
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi log left parenthesis 1 minus cosx right parenthesis space dx                                              ...(2)
    Adding (1) and (2), we get, 
    2 space straight I space equals space integral subscript 0 superscript straight pi open square brackets log left parenthesis 1 plus cosx right parenthesis plus log left parenthesis 1 minus cosx right parenthesis close square brackets dx space equals space integral subscript 0 superscript straight pi log open square brackets left parenthesis 1 plus cosx right parenthesis space left parenthesis 1 minus cosx right parenthesis close square brackets dx
           equals space integral subscript 0 superscript straight pi log left parenthesis 1 minus cos squared straight x right parenthesis space dx space equals space integral subscript 0 superscript straight pi log space left parenthesis sin squared straight x right parenthesis space dx space equals space 2 integral subscript 0 superscript straight pi log space sinx space dx
           equals space 2.2 space integral subscript 0 superscript straight pi over 2 end superscript log space sinx space dx                   open square brackets because space space log space sin left parenthesis straight pi minus straight x right parenthesis space equals space log space sinx close square brackets
             equals space 4 open parentheses negative straight pi over 2 log 2 close parentheses space equals space minus 2 space straight pi space log space 2
    therefore space space straight I space equals space minus straight pi space log space 2

    Question 212
    CBSEENMA12032642
    Question 213
    CBSEENMA12032645

    By using the properties of definite integrals, evaluate the following:
    integral subscript 0 superscript straight pi fraction numerator straight x space dx over denominator straight a squared space cos squared straight x plus straight b squared space sin squared straight x end fraction

    Solution

    Let I = integral subscript 0 superscript straight pi fraction numerator straight x space dx over denominator straight a squared cos squared straight x plus straight b squared sin squared straight x end fraction space space........(1)
    therefore space space space space space thin space straight I space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis dx over denominator straight a squared cos squared left parenthesis straight pi minus straight x right parenthesis plus straight b squared sin squared left parenthesis straight pi minus straight x right parenthesis end fraction space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space dx over denominator straight a squared cos squared straight x plus straight b squared sin squared straight x end fraction dx
                equals straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator straight a squared cos squared straight x plus straight b squared sin squared straight x end fraction dx space minus integral subscript 0 superscript straight pi fraction numerator xdx over denominator straight a squared space cos squared straight x plus straight b squared space sin squared straight x end fraction
     therefore space space space space space straight I space equals space straight pi integral subscript 0 superscript straight pi fraction numerator 1 over denominator straight a squared cos squared straight x plus straight b squared sin squared straight x end fraction dx minus 1                                         open square brackets because space of space left parenthesis 1 right parenthesis close square brackets
     therefore space space space 2 space straight I space equals space 2 integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator straight a squared space cos squared straight x plus straight b squared space sin squared straight x end fraction dx
    therefore space space 2 space space straight I space space equals space 2 integral subscript 0 superscript straight pi fraction numerator begin display style fraction numerator 1 over denominator cos squared straight x end fraction end style dx over denominator straight a squared plus straight b squared begin display style fraction numerator sin squared straight x over denominator cos squared straight x end fraction end style end fraction
    therefore space space space space straight I space equals space straight pi integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sec squared straight x space dx over denominator straight a squared plus straight b squared space tan squared straight x end fraction
    Put tan x =  t,   ∴ sec2 x dx = dt   When x = 0, t = tan 0 = 0
    When straight x space equals space straight pi over 2 comma space space space straight t space equals space tan straight pi over 2 space equals space infinity
    therefore space space space space space straight I space equals space straight pi integral subscript 0 superscript infinity fraction numerator dt over denominator straight a squared plus straight b squared straight t squared end fraction space equals space straight pi over straight b squared integral subscript 0 superscript infinity fraction numerator 1 over denominator open parentheses begin display style straight a over straight b end style close parentheses squared plus straight t squared end fraction dt
                 equals space straight pi over straight b squared. fraction numerator 1 over denominator begin display style straight a over straight b end style end fraction open square brackets tan to the power of negative 1 end exponent open parentheses fraction numerator straight t over denominator begin display style straight a over straight b end style end fraction close parentheses close square brackets subscript 0 superscript infinity space equals space fraction numerator straight pi over denominator straight a space straight b end fraction left parenthesis tan to the power of negative 1 end exponent infinity space minus space tan to the power of negative 1 end exponent 0 right parenthesis space equals space straight pi over ab open parentheses straight pi over 2 minus 0 close parentheses
    therefore space space space space straight I space equals space fraction numerator straight pi squared over denominator 2 ab end fraction

    Question 214
    CBSEENMA12032647

    Show that:
    integral subscript 0 superscript straight a fraction numerator square root of straight x over denominator square root of straight x plus square root of straight a minus straight x end root end fraction space equals space straight a over 2

    Solution

    Let I = integral subscript 0 superscript straight a fraction numerator square root of straight x over denominator square root of straight x plus square root of straight a minus straight x end root end fraction dx                  ...(1)
    therefore space space space straight I space equals space integral subscript 0 superscript straight a fraction numerator square root of straight a minus straight x end root over denominator square root of straight a minus straight x end root plus square root of straight a minus left parenthesis straight a minus straight x right parenthesis end root end fraction dx                    open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    rightwards double arrow   straight I space equals space integral subscript 0 superscript straight a fraction numerator square root of straight a minus straight x end root over denominator square root of straight a minus straight x end root plus square root of straight x end fraction dx             ...(2)
          Adding (1) and (2), we get,
    2 space straight I space equals space integral subscript 0 superscript straight a open parentheses fraction numerator square root of straight x over denominator square root of straight x plus square root of straight a minus straight x end root end fraction plus fraction numerator square root of straight a minus straight x end root over denominator square root of straight a minus straight x end root plus square root of straight x end fraction close parentheses dx space equals space integral subscript 0 superscript straight a fraction numerator square root of straight x plus square root of straight a minus straight x end root over denominator square root of straight x plus square root of straight a minus straight x end root end fraction dx space equals integral subscript 1 superscript straight a 1. space dx
           equals space open square brackets straight x close square brackets subscript 0 superscript straight a space equals space straight a space minus space 0
    rightwards double arrow space space space 2 space straight I space equals space straight a space space space space space space rightwards double arrow space space space space straight I space equals space straight a over 2

    Question 215
    CBSEENMA12032650

    Show that:
    integral subscript 0 superscript straight a fraction numerator 1 over denominator straight x plus square root of straight a squared minus straight x squared end root end fraction dx space equals space straight pi over 4

    Solution

    Let I = integral subscript 0 superscript straight a fraction numerator 1 over denominator straight x plus square root of straight a squared minus straight x squared end root end fraction
    Put x = a sin θ,    ∴ dx = a cos θ dθ
    When x = 0, a sin θ = 0 ⇒ sin θ = 0 ⇒ θ = 0
    when x = a, straight a space sin space straight theta space equals space straight a space space space space space space space space space space rightwards double arrow space space space space sin space straight theta space equals space 1 space space space space rightwards double arrow space space space straight theta space equals space straight pi over 2
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 1 over denominator straight a space sinθ space plus space square root of straight a squared minus straight a squared space sin squared space straight theta end root end fraction. space straight a space cosθ space dθ
             equals space integral subscript 0 superscript straight pi over 2 end superscript fraction numerator cos space straight theta space dθ over denominator sin space straight theta space plus space cos space straight theta end fraction space equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript fraction numerator 2 space cos space straight theta over denominator sin space straight theta space plus space cos space straight theta end fraction dθ
            equals space 1 half integral subscript 0 superscript straight pi over 2 end superscript fraction numerator left parenthesis cosθ space plus space sinθ right parenthesis space plus space left parenthesis cosθ space minus space sinθ right parenthesis over denominator cosθ plus sinθ end fraction dθ space equals 1 half integral subscript 0 superscript straight pi over 2 end superscript open parentheses 1 plus fraction numerator cosθ minus sinθ over denominator cosθ plus sinθ end fraction close parentheses dθ
             
              equals space 1 half open square brackets straight theta plus log open vertical bar cos space straight theta space plus space sin space straight theta close vertical bar close square brackets subscript 0 superscript straight pi over 2 end superscript
equals space 1 half open square brackets open parentheses straight pi over 2 plus log space open vertical bar cos straight pi over 2 plus sin straight pi over 2 close vertical bar close parentheses space minus space left parenthesis 0 plus log open vertical bar cos space 0 plus space sin space 0 close vertical bar right parenthesis close square brackets
equals space 1 half open square brackets open parentheses straight pi over 2 plus log space open vertical bar 0 plus 1 close vertical bar close parentheses space minus space left parenthesis 0 plus log space open vertical bar 1 plus 0 close vertical bar right parenthesis close square brackets space equals space 1 half open square brackets straight pi over 2 close square brackets space equals straight pi over 4

    Question 216
    CBSEENMA12032651

    Evaluate  integral subscript 1 superscript 4 straight f left parenthesis straight x right parenthesis space dx space space where space straight f left parenthesis straight x right parenthesis space equals space open vertical bar straight x minus 1 close vertical bar space plus space open vertical bar straight x minus 2 close vertical bar space plus space open vertical bar straight x minus 3 close vertical bar

    Solution

    Here,        straight f left parenthesis straight x right parenthesis space equals space open vertical bar straight x minus 1 close vertical bar space plus space open vertical bar straight x minus 2 close vertical bar plus space open vertical bar straight x minus 3 close vertical bar
    Let   I = integral subscript 1 superscript 4 straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 1 superscript 2 straight f left parenthesis straight x right parenthesis space dx plus integral subscript 2 superscript 3 straight f left parenthesis straight x right parenthesis space dx plus integral subscript 3 superscript 4 straight f left parenthesis straight x right parenthesis space dx
               equals space integral subscript 1 superscript 2 open square brackets left parenthesis straight x minus 1 right parenthesis space minus space left parenthesis straight x minus 2 right parenthesis space minus space left parenthesis straight x minus 3 right parenthesis close square brackets dx space plus space integral subscript 2 superscript 3 open square brackets left parenthesis straight x minus 1 right parenthesis space plus left parenthesis straight x minus 2 right parenthesis space minus space left parenthesis straight x minus 3 right parenthesis close square brackets dx
                                                                              plus integral subscript 3 superscript 4 open square brackets left parenthesis straight x minus 1 right parenthesis plus left parenthesis straight x minus 2 right parenthesis plus left parenthesis straight x minus 3 right parenthesis close square brackets dx
               equals space integral subscript 1 superscript 2 left parenthesis negative straight x plus 4 right parenthesis space dx plus space integral subscript 2 superscript 3 straight x space dx space plus integral subscript 3 superscript 4 left parenthesis 3 straight x minus 6 right parenthesis space dx
equals space open square brackets negative straight x squared over 2 plus 4 straight x close square brackets subscript 1 superscript 2 space plus space open square brackets straight x squared over 2 close square brackets subscript 2 superscript 3 plus open square brackets fraction numerator 3 straight x squared over denominator 2 end fraction minus 6 straight x close square brackets subscript 3 superscript 4
equals left parenthesis negative 2 plus 8 right parenthesis space space minus space open parentheses negative 1 half plus 4 close parentheses plus open parentheses 9 over 2 minus 2 close parentheses space plus space left parenthesis 24 minus 24 right parenthesis space minus space open parentheses 27 over 2 minus 18 close parentheses
equals space 6 minus 7 over 2 plus 5 over 2 plus 0 plus 9 over 2 space equals space 19 over 2

    Question 217
    CBSEENMA12032653

    Evaluate:  integral subscript negative 5 end subscript superscript 0 space straight f left parenthesis straight x right parenthesis space dx comma space space where space straight f left parenthesis straight x right parenthesis space equals space open vertical bar straight x close vertical bar plus open vertical bar straight x plus 2 close vertical bar plus open vertical bar straight x plus 5 close vertical bar.

    Solution

    Here straight f left parenthesis straight x right parenthesis space equals space open vertical bar straight x close vertical bar plus open vertical bar straight x plus 2 close vertical bar plus open vertical bar straight x plus 5 close vertical bar
    Let I = integral subscript negative 5 end subscript superscript 0 space straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript negative 5 end subscript superscript negative 2 end superscript straight f left parenthesis straight x right parenthesis space dx space plus space integral subscript negative 2 end subscript superscript 0 space straight f left parenthesis straight x right parenthesis space dx
             equals space integral subscript negative 5 end subscript superscript negative 2 end superscript open square brackets open vertical bar straight x close vertical bar plus open vertical bar straight x plus 2 close vertical bar plus open vertical bar straight x plus 5 close vertical bar close square brackets dx plus integral subscript negative 2 end subscript superscript 0 open square brackets open vertical bar straight x close vertical bar plus open vertical bar straight x plus 2 close vertical bar space plus open vertical bar straight x plus 5 close vertical bar close square brackets dx
    equals space integral subscript negative 5 end subscript superscript negative 2 end superscript left square bracket negative straight x minus left parenthesis straight x plus 2 right parenthesis plus left parenthesis straight x plus 5 right parenthesis right square bracket space dx space plus space integral subscript negative 2 end subscript superscript 0 open square brackets negative straight x plus left parenthesis straight x plus 2 right parenthesis plus left parenthesis straight x plus 5 right parenthesis close square brackets space dx
equals space integral subscript negative 5 end subscript superscript negative 2 end superscript left parenthesis negative straight x minus straight x minus 2 plus straight x plus 5 right parenthesis space dx plus integral subscript negative 2 end subscript superscript 0 left parenthesis negative straight x plus straight x plus 2 plus straight x plus 5 right parenthesis space dx
equals space integral subscript negative 5 end subscript superscript negative 2 end superscript left parenthesis negative straight x plus 3 right parenthesis space dx plus integral subscript negative 2 end subscript superscript 0 left parenthesis straight x plus 7 right parenthesis space dx space equals space open square brackets negative straight x squared over 2 plus 3 straight x close square brackets subscript negative 5 end subscript superscript 2 plus open square brackets straight x squared over 2 plus 7 straight x close square brackets subscript negative 2 end subscript superscript 0
equals left parenthesis negative 2 minus 6 right parenthesis minus open parentheses negative 25 over 2 minus 15 close parentheses plus left parenthesis 0 plus 0 right parenthesis minus left parenthesis 2 minus 14 right parenthesis space equals space minus 8 plus 55 over 2 plus 12 space equals 63 over 2.

    Question 218
    CBSEENMA12032655

    Evaluate: integral subscript negative 5 end subscript superscript 0 straight f left parenthesis straight x right parenthesis space dx comma space space space where space straight f left parenthesis straight x right parenthesis space equals space open vertical bar straight x close vertical bar plus open vertical bar straight x plus 3 close vertical bar plus open vertical bar straight x plus 6 close vertical bar.

    Solution
    Here f (x) = | x | + | x + 3 | + | x + 6 |
    Let I = integral subscript negative 5 end subscript superscript 0 straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript negative 5 end subscript superscript negative 3 end superscript straight f left parenthesis straight x right parenthesis space dx space plus space integral subscript negative 3 end subscript superscript 0 straight f left parenthesis straight x right parenthesis space dx
            equals space integral subscript negative 5 end subscript superscript negative 3 end superscript open square brackets open vertical bar straight x close vertical bar plus open vertical bar straight x plus 3 close vertical bar plus open vertical bar straight x plus 6 close vertical bar close square brackets space dx space space plus space integral subscript negative 3 end subscript superscript 0 space open square brackets open vertical bar straight x close vertical bar plus open vertical bar straight x plus 3 close vertical bar plus open vertical bar straight x plus 6 close vertical bar close square brackets dx
equals integral subscript negative 5 end subscript superscript negative 3 end superscript open square brackets negative straight x minus left parenthesis straight x plus 3 right parenthesis plus left parenthesis straight x plus 6 right parenthesis close square brackets dx plus integral subscript negative 3 end subscript superscript 0 open square brackets negative straight x plus left parenthesis straight x plus 3 right parenthesis plus left parenthesis straight x plus 6 right parenthesis close square brackets dx
equals integral subscript negative 5 end subscript superscript negative 3 end superscript left parenthesis negative straight x minus straight x minus 3 plus straight x plus 6 right parenthesis dx plus integral subscript negative 3 end subscript superscript 0 left parenthesis negative straight x plus straight x plus 3 plus straight x plus 6 right parenthesis space dx
equals space integral subscript negative 5 end subscript superscript negative 3 end superscript left parenthesis negative straight x plus 3 right parenthesis dx plus integral subscript negative 3 end subscript superscript 0 left parenthesis straight x plus 9 right parenthesis space dx space equals space open square brackets negative straight x squared over 2 plus 3 straight x close square brackets subscript negative 5 end subscript superscript negative 3 end superscript space plus space open square brackets straight x squared over 2 plus 9 straight x close square brackets subscript negative 3 end subscript superscript 0
            equals space open parentheses negative 9 over 2 minus 9 close parentheses space minus space open parentheses negative 25 over 2 minus 15 close parentheses plus left parenthesis 0 plus 0 right parenthesis minus open parentheses 9 over 2 minus 27 close parentheses minus 27 over 2 plus 55 over 2 plus 45 over 2 space equals space 73 over 2
    Question 219
    CBSEENMA12032657

    If  [ x ] stands for integral part of x, then show that integral subscript 0 superscript 1 left square bracket 5 space straight x right square bracket space dx space equals space 2.

    Solution

    Since open square brackets 5 space straight x close square brackets has integral values at x = 0,  1 fifth comma space 2 over 5 comma space 3 over 5 comma space 4 over 5 comma space 1
    therefore space space space space left square bracket 5 space straight x right square bracket is discontinuous at x = 0, 1 fifth comma space 2 over 5 comma space 3 over 5 comma space 4 over 5 comma space 1
    therefore space space straight I space equals space integral subscript 0 superscript 1 left square bracket space 5 space straight x right square bracket space dx space equals space integral subscript 0 superscript 1 fifth end superscript left square bracket space 5 space straight x right square bracket space dx space plus space integral subscript 1 fifth end subscript superscript 2 over 5 end superscript left square bracket space 5 space straight x right square bracket space dx space plus space integral subscript 2 over 5 end subscript superscript 3 over 5 end superscript left square bracket 5 space straight x right square bracket space dx plus integral subscript 3 over 5 end subscript superscript 4 over 5 end superscript left square bracket 5 space straight x right square bracket space dx space plus space integral subscript 4 over 5 end subscript superscript 1 left square bracket 5 space straight x right square bracket space dx
    equals space integral subscript 0 superscript 1 fifth end superscript left parenthesis 0 right parenthesis space dx space plus space integral subscript 1 fifth end subscript superscript 2 over 5 end superscript left parenthesis 1 right parenthesis space dx space plus space integral subscript 2 over 5 end subscript superscript 3 over 5 end superscript left parenthesis 2 right parenthesis space dx space plus space integral subscript 3 over 5 end subscript superscript 4 over 5 end superscript left parenthesis 3 right parenthesis space dx space plus space integral subscript 4 over 5 end subscript superscript 1 left parenthesis 4 right parenthesis space dx
             equals 0 plus open square brackets straight x close square brackets subscript 1 fifth end subscript superscript 2 over 5 end superscript plus 2 open square brackets straight x close square brackets subscript 2 over 5 end subscript superscript 3 over 5 end superscript plus 3 open square brackets straight x close square brackets subscript 3 over 5 end subscript superscript 4 over 5 end superscript plus space 4 open square brackets straight x close square brackets subscript 4 over 5 end subscript superscript 1
equals space 0 plus open parentheses 2 over 5 minus 1 fifth close parentheses plus 2 open parentheses 3 over 5 minus 2 over 5 close parentheses plus 3 open parentheses 4 over 5 minus 3 over 5 close parentheses plus 4 open parentheses 1 minus 4 over 5 close parentheses
equals space 0 plus 1 fifth plus 2 over 5 plus 3 over 5 plus 4 over 5 equals space space 2

    Question 220
    CBSEENMA12032658

    Show that integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space straight g left parenthesis straight x right parenthesis space dx space equals space 2 space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx comma space space if space straight f and g are defined as f(x) = f(a - x) and g(x) + g(a-x) = 4

    Solution

    We have
    f(x) = f(a-x)     ...(1)
    and g (x) + g (a – x) = 4    ...(2)
    Let I =                                                 ...(3)
          equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space straight g left parenthesis straight a minus straight x right parenthesis space dx                  open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
           equals space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space space open curly brackets 4 minus straight g left parenthesis straight x right parenthesis close curly brackets space dx                                           open square brackets because space of space left parenthesis 1 right parenthesis comma space left parenthesis 2 right parenthesis close square brackets
           equals 4 integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space minus space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space straight g left parenthesis straight x right parenthesis space dx
    therefore space space space space straight I space equals space 4 integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space minus space 1                                               left square bracket because space of space space left parenthesis 3 right parenthesis right square bracket
    therefore space space 2 space straight I space equals space 4 integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx
therefore space space space space straight I space equals space 2 integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx

    Question 221
    CBSEENMA12032660

    Evaluate: 
    integral subscript 0 superscript 1 cot to the power of negative 1 end exponent left parenthesis 1 minus straight x plus straight x squared right parenthesis dx.

    Solution

    Let
    I = integral subscript 0 superscript 1 cot to the power of negative 1 end exponent left parenthesis 1 minus straight x plus straight x squared right parenthesis dx
      equals space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent open parentheses fraction numerator 1 over denominator 1 minus straight x plus straight x squared end fraction close parentheses dx space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space cot to the power of negative 1 end exponent straight x space equals space tan to the power of negative 1 end exponent 1 over straight x close square brackets
       equals space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent open square brackets fraction numerator straight x plus left parenthesis 1 minus straight x right parenthesis over denominator 1 minus straight x left parenthesis 1 minus straight x right parenthesis end fraction close square brackets dx space equals space integral subscript 0 superscript 1 open square brackets tan to the power of negative 1 end exponent straight x plus tan to the power of negative 1 end exponent left parenthesis 1 minus straight x right parenthesis close square brackets dx
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space tan to the power of negative 1 end exponent straight x plus tan to the power of negative 1 end exponent straight y space equals space tan to the power of negative 1 end exponent open parentheses fraction numerator straight x plus straight y over denominator 1 minus xy end fraction close parentheses close square brackets
equals space integral subscript 0 superscript 1 space tan to the power of negative 1 end exponent xdx space plus space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent left parenthesis 1 minus straight x right parenthesis space dx
equals space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent straight x space dx plus integral subscript 0 superscript 1 tan to the power of negative 1 end exponent left curly bracket 1 minus left parenthesis 1 minus straight x right parenthesis right curly bracket space dx
equals space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent straight x space dx plus integral subscript 0 superscript 1 tan to the power of negative 1 end exponent straight x space dx space equals space 2 integral subscript 0 superscript 1 tan to the power of negative 1 end exponent straight x. space 1 space dx
        equals space 2 open square brackets left parenthesis tan to the power of negative 1 end exponent space straight x right parenthesis space left parenthesis straight x right parenthesis close square brackets subscript 0 superscript 1 space minus space 2 integral subscript 0 superscript 1 fraction numerator 1 over denominator 1 plus straight x squared end fraction cross times straight x space dx
equals 2 space open square brackets straight x space tan to the power of negative 1 end exponent straight x close square brackets subscript 0 superscript 1 space minus space integral subscript 0 superscript 1 fraction numerator 2 straight x over denominator 1 plus straight x squared end fraction dx space equals space 2 open square brackets straight x space tan to the power of negative 1 end exponent straight x close square brackets subscript 0 superscript 1 space minus space open square brackets log left parenthesis 1 plus straight x right parenthesis squared close square brackets subscript 0 superscript 1
equals space 2 left square bracket tan to the power of negative 1 end exponent space 1 space minus space 0 right square bracket space minus space left square bracket log space 2 space minus space log space 1 right square bracket
equals space 2 open parentheses straight pi over 4 minus 0 close parentheses space space minus space left parenthesis log space 2 space minus space 0 right parenthesis space equals space straight pi over 2 minus log space 2

    Question 222
    CBSEENMA12032663

    The value of integral subscript negative straight pi over 2 end subscript superscript straight pi over 2 end superscript left parenthesis straight x cubed plus straight x space cosx space plus space tan to the power of 5 straight x plus 1 right parenthesis space dx space is

    • 0

    • 2

    • straight pi
    • 1

    Solution

    C.

    straight pi

    Let
            straight I space equals space integral subscript negative straight pi over 2 end subscript superscript straight pi over 2 end superscript space left parenthesis straight x cubed plus straight x space cosx space plus tan to the power of 5 straight x space plus space 1 right parenthesis dx
    therefore space space space space space space space space equals space integral subscript negative straight pi over 2 end subscript superscript straight pi over 2 end superscript left parenthesis straight x cubed plus straight x space cosx plus tan to the power of 5 straight x right parenthesis space dx space plus space integral subscript straight pi over 2 end subscript superscript straight pi over 2 end superscript space 1 space dx space equals space 0 plus open square brackets straight x close square brackets subscript negative straight pi over 2 end subscript superscript straight pi over 2 end superscript
open square brackets because space space straight x cubed plus straight x space cosx plus space tan to the power of 5 straight x space is space odd space function space and space so space integral subscript negative straight pi over 2 end subscript superscript bevelled straight pi over 2 end superscript left parenthesis straight x cubed plus straight x space cosx plus space tan to the power of 5 straight x right parenthesis space dx space equals space 0 close square brackets
space space space space space space equals space straight pi over 2 minus open parentheses negative straight pi over 2 close parentheses space equals space straight pi over 2 plus straight pi over 2 space equals space straight pi
      therefore space space space space left parenthesis straight C right parenthesis space is space correct space answer.

    Question 223
    CBSEENMA12032665

    The value of integral subscript 0 superscript straight pi over 2 end superscript space log space space open parentheses fraction numerator 4 plus 3 space sinx over denominator 4 plus 3 space cosx end fraction close parentheses dx is

    • 2

    • 3 over 4
    • 0

    • -2

    Solution

    Let
    I = integral subscript 0 superscript straight pi over 2 end superscript space log open parentheses fraction numerator 4 plus 3 space sin space straight x over denominator 4 plus 3 space cosx end fraction close parentheses dx                               ...(1)
     equals space integral subscript 0 superscript straight pi log space open curly brackets fraction numerator 4 plus 3 space sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator 4 plus 3 space cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction close curly brackets dx                    open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
      equals space integral subscript 0 superscript straight pi over 2 end superscript space log space open parentheses fraction numerator 4 plus 3 space cosx over denominator 4 plus 3 space sinx end fraction close parentheses dx
    equals space integral subscript 0 superscript straight pi over 2 end superscript space log space open parentheses fraction numerator 4 plus 3 space sinx over denominator 4 plus 3 space cosx end fraction close parentheses to the power of negative 1 end exponent space dx space equals space minus integral subscript 0 superscript straight pi over 2 end superscript log space open parentheses fraction numerator 4 plus 3 space sinx over denominator 4 plus 3 space cosx end fraction close parentheses dx
    therefore space space space space space space straight I space equals space minus 1                                                       left square bracket because space of space left parenthesis 1 right parenthesis right square bracket
    therefore space space space 2 space straight I space equals space 0 space space space space space space space rightwards double arrow space space space space straight I space equals space 0
    therefore space space left parenthesis straight C right parenthesis space is space correct space answer

    Question 224
    CBSEENMA12032666

    If straight f left parenthesis straight a plus straight b minus straight x right parenthesis space equals space straight f left parenthesis straight x right parenthesis comma space space then space integral subscript straight a superscript straight b straight x space straight f left parenthesis straight x right parenthesis space dx is equal to

    • fraction numerator straight a plus straight b over denominator 2 end fraction integral subscript straight a superscript straight b straight f left parenthesis straight b minus straight x right parenthesis space dx
    • fraction numerator straight a plus straight b over denominator 2 end fraction integral subscript straight a superscript straight b straight f left parenthesis straight b plus straight x right parenthesis space dx
    • fraction numerator straight b minus straight a over denominator 2 end fraction integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx
    • fraction numerator straight a plus straight b over denominator 2 end fraction integral subscript straight a superscript straight b space straight f left parenthesis straight x right parenthesis space dx

    Solution

    D.

    fraction numerator straight a plus straight b over denominator 2 end fraction integral subscript straight a superscript straight b space straight f left parenthesis straight x right parenthesis space dx

    Let I = integral subscript straight a superscript straight b space straight x space straight f left parenthesis straight x right parenthesis space dx                              ...(1)
    therefore space space space space straight I space equals space integral subscript straight a superscript straight b left parenthesis straight a plus straight b minus straight x right parenthesis space straight f left parenthesis straight a plus straight b minus straight x right parenthesis space dx space space space space space space space space space space space space space open square brackets because space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f left parenthesis straight a plus straight b minus straight x right parenthesis space dx close square brackets
therefore space space space space straight I space equals space integral subscript straight a superscript straight b left parenthesis straight a plus straight b minus straight x right parenthesis space dx space space space space space space space space space... left parenthesis 2 right parenthesis
                                                                                     left square bracket because space space straight f left parenthesis straight a plus straight b minus straight x right parenthesis space equals space straight f left parenthesis straight x right parenthesis right square bracket
    Adding (1) and (2), we get,
             2 space straight I space equals space integral subscript straight a superscript straight b left parenthesis straight x plus straight a plus straight b minus straight x right parenthesis space straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b left parenthesis straight a plus straight b right parenthesis space straight f left parenthesis straight x right parenthesis space dx
    therefore space space space 2 space space straight I space equals space left parenthesis straight a plus straight b right parenthesis space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space space space rightwards double arrow space space space space straight I space equals space fraction numerator straight a plus straight b over denominator 2 end fraction integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx
therefore space space space integral subscript straight a superscript straight b space straight x space straight f left parenthesis straight x right parenthesis space dx space equals space fraction numerator straight a plus straight b over denominator 2 end fraction integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx
    therefore space space space left parenthesis straight D right parenthesis space is space correct space answer.

    Question 225
    CBSEENMA12032668

    The value of integral subscript 0 superscript 1 space tan to the power of negative 1 end exponent open parentheses fraction numerator 2 straight x minus 1 over denominator 1 plus straight x minus straight x squared end fraction close parentheses dx is 

    • 1

    • 0

    • -1

    • straight pi over 4

    Solution

    B.

    0

    Let I = integral subscript 0 superscript 1 tan to the power of negative 1 end exponent open parentheses fraction numerator 2 straight x minus 1 over denominator 1 plus straight x minus straight x squared end fraction close parentheses dx
             equals space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent open curly brackets fraction numerator straight x plus left parenthesis straight x minus 1 right parenthesis over denominator 1 minus straight x left parenthesis straight x minus 1 right parenthesis end fraction close curly brackets space dx space equals space integral subscript 0 superscript 1 left square bracket tan to the power of negative 1 end exponent straight x space plus space tan to the power of negative 1 end exponent left parenthesis straight x minus 1 right parenthesis right square bracket space dx
    therefore space space space space space straight I space equals integral subscript 0 superscript 1 space open square brackets tan to the power of negative 1 end exponent minus space tan to the power of negative 1 end exponent left parenthesis 1 minus straight x right parenthesis close square brackets dx                         ...(1)
    Again, straight I space equals space integral subscript 0 superscript 1 open square brackets tan to the power of negative 1 end exponent left parenthesis 1 minus straight x right parenthesis space minus space tan to the power of negative 1 end exponent open curly brackets 1 minus left parenthesis 1 minus straight x close curly brackets close square brackets space dx
                                                                  open square brackets because space space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f left parenthesis straight a plus straight b minus straight x right parenthesis space dx close square brackets
                     equals space integral subscript 0 superscript 1 left square bracket tan to the power of negative 1 end exponent left parenthesis 1 minus straight x right parenthesis space minus space tan to the power of negative 1 end exponent straight x right square bracket dx space equals space integral subscript 0 superscript 1 left square bracket tan to the power of negative 1 end exponent straight x space minus space tan to the power of negative 1 end exponent left parenthesis 1 minus straight x right parenthesis right square bracket space dx
    therefore space space space space space space straight I space equals space minus straight I space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space open square brackets because space of space left parenthesis 1 right parenthesis close square brackets
    therefore space space space space space space 2 space space straight I space equals space 0 space space space space space space space space space space space rightwards double arrow space space space space space straight I space equals space 0
therefore space space space integral subscript 0 superscript 1 tan to the power of negative 1 end exponent open parentheses fraction numerator 2 straight x minus 1 over denominator 1 plus straight x minus straight x squared end fraction close parentheses dx space equals space 0
    therefore space space space left parenthesis straight B right parenthesis space is space correct space answer.

    Question 226
    CBSEENMA12032670

    Evaluate integral subscript 0 superscript straight pi over 2 end superscript log space sinx space dx.

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript space log space sinx space dx                             ...(1)
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript log space sin open parentheses straight pi over 2 minus straight x close parentheses space dx               open square brackets because space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
    or     straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space log space cosx space dx                         ...(2)
    Adding (1) and (2), we get,
          2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript left parenthesis log space sinx space plus space log space cosx right parenthesis space dx space equals space integral subscript 0 superscript straight pi over 2 end superscript log space left parenthesis sinx space cosx right parenthesis space dx
                equals space integral subscript 0 superscript straight pi over 2 end superscript log space open parentheses fraction numerator 2 space sinx space cos space straight x over denominator 2 end fraction close parentheses dx space equals space integral subscript 0 superscript straight pi over 2 end superscript log space open parentheses fraction numerator sin space 2 straight x over denominator 2 end fraction close parentheses dx
    therefore space space space 2 space straight I space equals space integral subscript 0 superscript straight pi over 2 end superscript space log space sin space 2 straight x space dx space space minus space integral subscript 0 superscript straight pi over 2 end superscript space log space 2 space dx
therefore space space space 2 space straight I space equals space straight I subscript 1 minus space straight I subscript 2 space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space... left parenthesis 3 right parenthesis
    where   straight I subscript 2 space equals space integral subscript 0 superscript straight pi over 2 end superscript log space 2 space dx space equals space log space 2 space integral subscript 0 superscript straight pi over 2 end superscript 1. space dx
                     equals space log space 2. space open square brackets straight x close square brackets subscript 0 superscript straight pi over 2 end superscript space equals space space log space 2. space open square brackets straight pi over 2 minus 0 close square brackets space equals space straight pi over 2 space log space 2
    and  straight I subscript 1 space equals space integral subscript 0 superscript straight pi over 2 end superscript space log space sin space 2 straight x space dx
    Put      2 x = t          or  straight x space equals space straight t over 2 space space space space space space space space space space space space space space space space space rightwards double arrow space space space space dx space equals space 1 half dt
    When   x = 0,  t  = 0
    When    straight x space equals space straight pi over 2 comma space space space straight t space equals space straight pi
    therefore space space space straight I subscript 1 space equals space integral subscript 0 superscript straight pi log space sint. space 1 half dt space equals space 1 half integral subscript 0 superscript straight pi log space sint space dt space equals space 1 half integral subscript 0 superscript straight pi log space sinx space dx
                                                                                   open square brackets because space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f left parenthesis straight t right parenthesis space dt close square brackets
               equals space 1 half. space 2 space integral subscript 0 superscript straight pi over 2 end superscript log. space sinx space dx space equals space integral subscript 0 superscript straight pi over 2 end superscript log space sinx space dx
                                              open square brackets because space space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space 2 integral subscript 0 superscript straight a over 2 end superscript straight f left parenthesis straight x right parenthesis space dx space when space straight f left parenthesis straight a minus straight x right parenthesis space equals space straight f left parenthesis straight x right parenthesis close square brackets
    therefore space space space space straight I subscript 1 space equals space 1
therefore space space space space from space left parenthesis 3 right parenthesis comma space space 2 space space straight I space equals space straight I space minus space straight pi over 2 log space 2 space space space rightwards double arrow space space straight I space equals space minus straight pi over 2 space log space 2 space
rightwards double arrow space space space integral subscript 0 superscript straight pi over 2 end superscript space log space sinx space dx space equals space minus straight pi over 2 log space 2
    Cor. integral subscript 0 superscript straight pi over 2 end superscript log space cosx space dx space equals space integral subscript 0 superscript straight pi over 2 end superscript log space cos open parentheses straight pi over 2 minus straight x close parentheses dx space equals space integral subscript 0 superscript straight pi over 2 end superscript log space sinx space dx space equals space minus straight pi over 2 log space 2

    Question 227
    CBSEENMA12032673

    Evaluate the definite integral:
    integral subscript 2 superscript 3 fraction numerator 1 over denominator straight x squared minus 1 end fraction dx

    Solution

    Let I = integral subscript 2 superscript 3 fraction numerator dx over denominator straight x squared minus 1 end fraction space equals space 1 half open square brackets log space open parentheses fraction numerator straight x minus 1 over denominator straight x plus 1 end fraction close parentheses close square brackets subscript 2 superscript 3
           equals space 1 half open square brackets log space open parentheses fraction numerator 3 minus 1 over denominator 3 plus 1 end fraction close parentheses minus log space open parentheses fraction numerator 2 minus 1 over denominator 2 plus 1 end fraction close parentheses close square brackets space equals space 1 half open parentheses log space 1 half minus log space 1 third close parentheses
equals space 1 half log open parentheses 1 half cross times 3 over 1 close parentheses space equals space 1 half log 3 over 2

    Question 228
    CBSEENMA12032676

    Evaluate the definite integral:
    integral subscript 0 superscript 1 divided by square root of 2 end superscript fraction numerator sin to the power of negative 1 end exponent straight x over denominator left parenthesis 1 minus straight x squared right parenthesis to the power of begin display style 3 over 2 end style end exponent end fraction dx

    Solution

    Let I = integral subscript 0 superscript 1 divided by square root of 2 end superscript fraction numerator sin to the power of negative 1 end exponent straight x over denominator left parenthesis 1 minus straight x squared right parenthesis to the power of begin display style 3 over 2 end style end exponent end fraction dx
    Put straight x space equals space sin space straight theta space space space or space space straight theta space equals space sin to the power of negative 1 end exponent straight x comma space space space space therefore space space space dx space equals space space cosθ space dθ
    When x = 0,   sin space straight theta space equals space 0 space space space space space space space space space space rightwards double arrow space space space space space space straight theta space space equals 0
    When straight x space equals space 1 half comma space space sin space straight theta space equals space fraction numerator 1 over denominator square root of 2 end fraction space space space space space space space rightwards double arrow space space space space straight theta space equals space straight pi over 4
    therefore space space space space straight I space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator straight theta over denominator left parenthesis 1 minus sin squared straight theta right parenthesis to the power of begin display style 3 over 2 end style end exponent end fraction cos space straight theta space dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator straight theta space cosθ over denominator cos cubed straight theta space end fraction dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript fraction numerator straight theta over denominator cos squared straight theta end fraction dθ
             equals space integral subscript 0 superscript straight pi over 4 end superscript space straight theta space sec squared space straight theta space dθ space equals space open square brackets straight theta space tan space straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript space minus space integral subscript 0 superscript straight pi over 4 end superscript 1. space tan space straight theta space dθ
equals space open square brackets straight theta space tan space straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript plus open square brackets log space open vertical bar cos space straight theta close vertical bar close square brackets subscript 0 superscript straight pi over 4 end superscript
equals space open parentheses straight pi over 4 tan straight pi over 4 minus 0 close parentheses space plus space open square brackets log space open vertical bar cos space straight pi over 4 close vertical bar minus log space left parenthesis cos space 0 right parenthesis close square brackets
equals space straight pi over 4 cross times 1 space minus space 0 space plus space log space fraction numerator 1 over denominator square root of 2 end fraction minus space log space 1 space equals space straight pi over 4 plus log space 1 space minus space log space 2 to the power of 1 half end exponent minus 0 space equals space straight pi over 4 minus 1 half log space 2

    Question 229
    CBSEENMA12032682

    Evaluate:
    integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator straight a space cosx plus straight b space sinx end fraction. space straight a comma space straight b space greater than space 0

    Solution

    Let I = integral subscript 0 superscript straight pi over 2 end superscript fraction numerator dx over denominator acosx plus bsinx end fraction
    Put tan space straight x over 2 space equals space straight t space space space or space straight x over 2 space equals space tan to the power of negative 1 end exponent space straight t space rightwards double arrow space space straight x space equals space 2 space tan to the power of negative 1 end exponent straight t space space space space rightwards double arrow space space space dx space equals space fraction numerator 2 over denominator 1 plus straight t squared end fraction dt
    When straight x space equals space 0 comma space space straight t space equals space tan space 0 space equals space 0
    When  straight x space equals space straight pi over 2 comma space straight t space equals space tan straight pi over 4 space equals space 1
    Also sinx space equals space fraction numerator 2 space tan space begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals fraction numerator 2 straight t over denominator 1 minus straight t squared end fraction comma space space cosx space equals space fraction numerator 1 minus tan squared begin display style straight x over 2 end style over denominator 1 plus tan squared begin display style straight x over 2 end style end fraction space equals space fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction
    therefore space space space space straight I space equals space integral subscript 0 superscript 1 fraction numerator begin display style fraction numerator 2 over denominator 1 plus straight t squared end fraction end style dt over denominator straight a open parentheses begin display style fraction numerator 1 minus straight t squared over denominator 1 plus straight t squared end fraction end style close parentheses plus straight b open parentheses begin display style fraction numerator 2 straight t over denominator 1 plus straight t squared end fraction end style close parentheses end fraction space equals space integral subscript 0 superscript 1 fraction numerator 2 dt over denominator straight a left parenthesis 1 minus straight t squared right parenthesis plus 2 bt end fraction
                  equals space 2 over straight a integral subscript 0 superscript 1 fraction numerator dt over denominator 1 minus straight t squared plus begin display style fraction numerator 2 straight b over denominator straight a end fraction end style straight t end fraction straight t space equals space 2 over straight a integral subscript 0 superscript 1 fraction numerator dt over denominator 1 minus open parentheses straight t squared minus begin display style fraction numerator 2 straight b over denominator straight a end fraction end style straight t close parentheses end fraction
equals space 2 over straight a integral subscript 0 superscript 1 fraction numerator dt over denominator open parentheses 1 plus begin display style straight b squared over straight a squared end style close parentheses minus open parentheses straight t squared minus begin display style fraction numerator 2 straight b over denominator straight a end fraction end style straight t plus begin display style straight b squared over straight a squared end style close parentheses end fraction space equals space 2 over straight a integral subscript 0 superscript 1 fraction numerator dt over denominator open parentheses begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction end style close parentheses squared minus open parentheses straight t minus begin display style straight b over straight a end style close parentheses squared end fraction
equals space 2 over straight a fraction numerator 1 over denominator begin display style fraction numerator 2 square root of straight a squared plus straight b squared end root over denominator straight a end fraction end style end fraction open square brackets fraction numerator open vertical bar log space begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction end style plus open parentheses straight t minus begin display style straight b over straight a end style close parentheses close vertical bar over denominator begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction end style minus open parentheses straight t minus begin display style straight b over straight a end style close parentheses end fraction close square brackets subscript 0 superscript 1
    equals space fraction numerator 1 over denominator square root of straight a squared plus straight b squared end root end fraction open square brackets log open square brackets fraction numerator open parentheses begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction end style plus 1 minus begin display style straight b over straight a end style close parentheses over denominator begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction end style minus 1 plus begin display style straight b over straight a end style end fraction close square brackets minus space log space open parentheses fraction numerator begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction minus straight b over straight a end style over denominator begin display style fraction numerator square root of straight a squared plus straight b squared end root over denominator straight a end fraction plus straight b over straight a end style end fraction close parentheses close square brackets space
equals space fraction numerator 1 over denominator square root of straight a squared plus straight b squared end root end fraction open square brackets log space open parentheses fraction numerator square root of straight a squared plus straight b squared end root plus straight a minus straight b over denominator square root of straight a squared plus straight b squared end root minus straight a plus straight b end fraction close parentheses minus log space open parentheses fraction numerator square root of straight a squared plus straight b squared end root minus straight b over denominator square root of straight a squared plus straight b squared end root plus straight b end fraction close parentheses close square brackets
    space equals space fraction numerator 1 over denominator square root of straight a squared plus straight b squared end root end fraction space log space open parentheses fraction numerator square root of straight a squared plus straight b squared end root plus straight a minus straight b over denominator square root of straight a squared plus straight b squared end root minus straight a plus straight b end fraction cross times fraction numerator square root of straight a squared plus straight b squared end root plus straight b over denominator square root of straight a squared plus straight b squared end root minus straight b end fraction close parentheses
equals space fraction numerator 1 over denominator square root of straight a squared plus straight b squared end root end fraction log open parentheses fraction numerator straight a squared plus straight b squared plus ab minus straight b squared plus straight a square root of straight a squared plus straight b squared end root over denominator straight a squared plus straight b squared plus ab minus straight b squared minus straight a square root of straight a squared plus straight b squared end root end fraction close parentheses
equals space fraction numerator 1 over denominator square root of straight a squared plus straight b squared end root end fraction log open parentheses fraction numerator straight a plus straight b plus square root of straight a squared plus straight b squared end root over denominator straight a plus straight b minus square root of straight a squared plus straight b squared end root end fraction close parentheses

    Question 231
    CBSEENMA12035638

    space F i n d space colon integral fraction numerator left parenthesis 2 x minus 5 right parenthesis e to the power of 2 x end exponent over denominator left parenthesis 2 x minus 3 right parenthesis end fraction d x

    Solution

    Consider the given integral
    straight I space equals integral fraction numerator left parenthesis 2 straight x minus 5 right parenthesis straight e to the power of 2 straight x end exponent over denominator left parenthesis 2 straight x minus 3 right parenthesis cubed end fraction dx

Rewriting space the space above space integral space as

straight I space equals space integral straight e to the power of 2 straight x minus 3 end exponent space straight x space straight e cubed fraction numerator left parenthesis 2 straight x minus 3 minus 2 right parenthesis over denominator left parenthesis 2 straight x minus 3 right parenthesis cubed end fraction dx

equals space straight e cubed integral straight e to the power of 2 straight x minus 3 end exponent open square brackets fraction numerator left parenthesis 2 straight x minus 3 right parenthesis over denominator left parenthesis 2 straight x minus 3 right parenthesis cubed end fraction minus fraction numerator 2 over denominator left parenthesis 2 straight x minus 3 right parenthesis cubed end fraction close square brackets dx

equals space straight e cubed integral straight e to the power of 2 straight x minus 3 end exponent open square brackets fraction numerator 1 over denominator left parenthesis 2 straight x minus 3 right parenthesis squared end fraction minus fraction numerator 2 over denominator left parenthesis 2 straight x minus 3 right parenthesis cubed end fraction close square brackets dx

Let space us space consider comma space 2 straight x minus 3 space equals space straight t

rightwards double arrow space 2 dx space equals space dt

therefore space straight I equals straight e cubed integral straight e to the power of straight t open square brackets 1 over straight t squared minus 2 over straight t cubed close square brackets dt over 2

rightwards double arrow space straight I equals straight e cubed over 2 integral straight e to the power of straight t open square brackets fraction numerator straight t minus 2 over denominator straight t cubed end fraction close square brackets space dt

Let space straight f space left parenthesis straight t right parenthesis space equals 1 over straight t squared

straight f apostrophe left parenthesis straight t right parenthesis space equals space fraction numerator negative 2 over denominator straight t cubed end fraction

If space straight I space equals integral straight e to the power of straight t space end exponent left square bracket straight f space left parenthesis straight t right parenthesis space plus space straight f apostrophe left parenthesis straight t right parenthesis space right square bracket dt space then comma space straight I space equals space space straight e apostrophe straight f space left parenthesis straight t right parenthesis space plus space straight C

therefore space straight I space equals straight e cubed over 2 space straight x space straight e to the power of straight t space space straight x space straight f space left parenthesis straight t right parenthesis space plus space straight C

equals space straight e cubed over 2 space straight x space space straight e to the power of 2 straight x minus 3 end exponent space space straight x space fraction numerator 1 over denominator left parenthesis 2 straight x minus 3 right parenthesis squared end fraction space plus space straight C

equals fraction numerator straight e to the power of 2 straight x end exponent over denominator 2 left parenthesis 2 straight x minus 3 right parenthesis squared end fraction plus straight C

    Question 232
    CBSEENMA12035639

    Find space colon integral fraction numerator straight x squared plus straight x plus 1 over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction dx

    Solution
    Taking space the space given space function

straight I equals integral fraction numerator straight x squared plus straight x plus 1 over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction dx

Let space fraction numerator straight x squared space plus space straight x space plus space 1 over denominator left parenthesis straight x squared space plus space 1 right parenthesis space left parenthesis straight x space plus space 2 right parenthesis end fraction space space equals space fraction numerator straight A over denominator straight x space plus space 2 end fraction space plus space fraction numerator Bx space plus space straight C over denominator straight x squared plus 1 end fraction

equals space fraction numerator straight A left parenthesis straight x squared space plus space 1 right parenthesis space plus space left parenthesis Bx space space plus space straight C right parenthesis left parenthesis straight x space plus space 2 right parenthesis over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction

equals fraction numerator left parenthesis straight A plus straight B right parenthesis straight x squared plus left parenthesis 2 straight B plus straight C right parenthesis space straight x plus left parenthesis 2 straight C plus straight A right parenthesis over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction

Thus space equating space the space coefficients comma space we space have comma
straight A space plus space straight B space equals 1 space.. space left parenthesis straight i right parenthesis

2 straight B space space plus space straight C space equals space 1 space.. left parenthesis ii right parenthesis

2 straight C space plus space straight A space equals space 1 space.. space left parenthesis iii right parenthesis

solving space the space above space three space equations comma space we space have comma

straight A space equals 3 over 5 comma space straight B space equals 2 over 5 space and space straight C equals 1 fifth

therefore comma

fraction numerator straight x squared plus straight x plus 1 over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction space fraction numerator straight A over denominator straight x plus 2 end fraction plus fraction numerator Bx plus straight C over denominator straight x squared plus 1 end fraction

rightwards double arrow space fraction numerator straight x squared plus straight x plus 1 over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction space equals space fraction numerator 3 over denominator 5 left parenthesis straight x plus 2 right parenthesis end fraction space plus space fraction numerator 2 straight x plus 1 over denominator 5 left parenthesis straight x squared plus 1 right parenthesis end fraction

therefore comma
straight I equals integral fraction numerator straight x squared plus straight x plus 1 over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x plus 2 right parenthesis end fraction dx

equals integral open square brackets fraction numerator 3 over denominator 5 space left parenthesis straight x plus 2 right parenthesis end fraction plus fraction numerator 2 straight x plus 1 over denominator 5 left parenthesis straight x squared plus 1 right parenthesis end fraction dx close square brackets

equals 3 over 5 integral fraction numerator dx over denominator left parenthesis straight x plus 2 right parenthesis end fraction dx space plus space 1 fifth integral fraction numerator 2 straight x plus 1 over denominator left parenthesis straight x squared plus 1 right parenthesis end fraction dx

equals 3 over 5 log space left parenthesis straight x plus 2 right parenthesis space plus 1 fifth integral fraction numerator 2 straight x over denominator left parenthesis straight x squared plus 1 right parenthesis end fraction dx space plus 1 fifth integral fraction numerator dx over denominator left parenthesis straight x squared plus 1 right parenthesis end fraction

equals 3 over 5 log space left parenthesis straight x plus 2 right parenthesis space plus 1 fifth log space left parenthesis straight x squared plus 1 right parenthesis plus 1 fifth tan to the power of negative 1 end exponent space straight x space plus space straight C
    Question 233
    CBSEENMA12035640

    Evaluate space colon space integral subscript negative 2 end subscript superscript 2 fraction numerator straight x squared over denominator 1 plus 5 to the power of straight x end fraction dx.

    Solution
    Consider space the space given space integral
straight I equals integral subscript negative 2 end subscript superscript 2 fraction numerator straight x squared over denominator 1 plus 5 to the power of straight x end fraction dx space space.... left parenthesis straight i right parenthesis

Let space us space use space the space property comma

integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals integral subscript straight a superscript straight b straight f left parenthesis straight a plus straight b minus straight x right parenthesis dx

therefore space straight I space equals integral subscript negative 2 end subscript superscript 2 fraction numerator left parenthesis negative straight x right parenthesis squared over denominator 1 plus 5 to the power of negative straight x end exponent end fraction dx

equals integral subscript negative 2 end subscript superscript 2 fraction numerator 5 to the power of straight x space straight x squared over denominator 1 plus 5 to the power of straight x end fraction dx space.. space left parenthesis ii right parenthesis

Adding space equations space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis comma space we space have comma

2 straight I space equals integral subscript negative 2 end subscript superscript 2 fraction numerator 1 plus 5 to the power of straight x over denominator 1 plus 5 to the power of straight x end fraction space. space straight x squared dx

equals integral subscript negative 2 end subscript superscript 2 straight x squared dx

equals space open square brackets straight x cubed over 3 close square brackets subscript negative 2 end subscript superscript 2

equals space 1 third left square bracket 8 minus left parenthesis negative 8 right parenthesis right square bracket

equals space 1 third space left square bracket 16 right square bracket

rightwards double arrow space straight I space equals space 8 over 3
    Question 234
    CBSEENMA12035641

    Find colon space integral left parenthesis straight x plus 3 right parenthesis square root of 3 minus 4 straight x minus straight x squared space end root space dx.

    Solution
    straight I space equals integral left parenthesis straight x plus 3 right parenthesis square root of 3 minus 4 straight x minus straight x squared end root dx

Let space left parenthesis straight x space plus 3 right parenthesis space equals space straight A straight d over dx left parenthesis 3 minus 4 straight x minus straight x squared right parenthesis space plus space straight B space space space... space left parenthesis straight i right parenthesis

rightwards double arrow space space straight x space plus space 3 space equals space straight A left parenthesis negative 2 straight x minus 4 right parenthesis space plus space straight B

rightwards double arrow space straight x plus 3 space equals space minus 2 Ax minus 4 straight A plus straight B

therefore space minus 2 straight A space space equals space 1

rightwards double arrow space straight A space equals space minus 1 half

minus 4 straight A space plus space straight B space equals space 3

rightwards double arrow space minus 4 space open parentheses negative 1 half close parentheses plus space straight B space equals 3

rightwards double arrow space space straight B equals 1

therefore comma

straight I space equals integral open square brackets negative 1 half straight d over dx left parenthesis 3 minus 4 straight x minus straight x squared right parenthesis plus 1 close square brackets space square root of 3 minus 4 straight x minus straight x squared end root space dx

equals space space 1 half integral straight d over dx left parenthesis 3 minus 4 straight x minus straight x squared right parenthesis square root of 3 minus 4 straight x minus straight x squared end root dx space plus space integral square root of 3 minus 4 straight x minus straight x squared minus 4 plus 4 dx end root

equals space minus 1 half fraction numerator left parenthesis 3 minus 4 straight x minus straight x squared right parenthesis to the power of begin display style 3 over 2 end style end exponent over denominator 3 divided by 2 end fraction space plus space integral square root of 7 minus left parenthesis straight x plus 2 right parenthesis squared end root dx

equals space minus fraction numerator left parenthesis 3 minus 4 straight x minus straight x squared right parenthesis to the power of begin display style 3 over 2 end style end exponent over denominator 3 end fraction space plus space fraction numerator straight x plus 2 over denominator 2 end fraction square root of 7 minus left parenthesis straight x plus 2 right parenthesis squared dx end root

equals space minus fraction numerator left parenthesis 3 minus 4 straight x minus straight x squared right parenthesis to the power of begin display style 3 over 2 end style end exponent over denominator 3 end fraction space plus space fraction numerator straight x plus 2 over denominator 2 end fraction square root of 7 minus left parenthesis straight x plus 2 right parenthesis squared end root space plus space 7 over 2 sin to the power of negative 1 end exponent open parentheses fraction numerator straight x plus 2 over denominator square root of 7 end fraction close parentheses space space plus space straight C
    Question 235
    CBSEENMA12035645

    Find the coordinates of the foot of perpendicular drawn from the point A
    (-1,8,4) to the line joining the points B(0,-1,3) and C(2,-3,-1). Hence find the image of the point A in the line BC.

    Solution

    Suppose P be the foot of the perpendicular drawn from point A on the line joining
    points B and C.
    Let P’ (a, b, c) be the coordinates of the image of point A.
    fraction numerator straight x minus straight x subscript 1 over denominator straight x subscript 2 minus straight x subscript 1 end fraction space equals space fraction numerator straight y minus straight y subscript 1 over denominator straight y subscript 2 minus end subscript straight y subscript 1 end fraction space space equals space fraction numerator straight z minus straight z subscript 1 over denominator straight z subscript 2 minus straight z subscript 1 end fraction

fraction numerator straight x minus 0 over denominator 2 end fraction space equals space fraction numerator space straight y plus 1 over denominator negative 2 end fraction space equals space fraction numerator straight z minus 3 over denominator negative 4 end fraction space equals space straight lambda

General space coordinates space of space straight P space is space left parenthesis 2 straight lambda comma negative 2 straight lambda minus 1 comma negative 4 straight lambda plus 3 right parenthesis

Direction space ratio space of space AP space left parenthesis 2 straight lambda plus 1 comma negative 2 straight lambda minus 9 comma 4 straight lambda minus 1 right parenthesis

AP perpendicular BC

2 left parenthesis 2 straight lambda plus 1 right parenthesis minus 2 left parenthesis negative 2 straight lambda minus 9 right parenthesis minus 4 left parenthesis negative 4 straight lambda minus 1 right parenthesis equals 0

4 straight lambda plus 2 plus 4 straight lambda plus 18 plus 16 straight lambda plus 4 space equals 0

24 plus 24 straight lambda space equals 0

straight lambda equals negative 1

straight P left parenthesis negative 2 comma 1 comma 7 right parenthesis

Coordinates space of space foot space of space perpendicular space is space left parenthesis negative 2 comma 1 comma 7 right parenthesis

Coordinates space of space image space of space straight A space is space straight P to the power of apostrophe left parenthesis space straight a comma straight b comma straight c right parenthesis space is space

fraction numerator straight a minus 1 over denominator 2 end fraction equals negative 2 comma space straight a equals negative 3

fraction numerator straight b plus 8 over denominator 2 end fraction space equals space 1 comma space straight b equals negative 6

fraction numerator straight c plus 4 over denominator 2 end fraction space equals space 7 comma space straight c equals space 10

straight P apostrophe space left parenthesis negative 3 comma negative 6 comma 10 right parenthesis

    Question 236
    CBSEENMA12035646
    Question 238
    CBSEENMA12035648

    Three numbers are selected at random (without replacement) from first six positive integers. Let X denote the largest of the three numbers obtained. Find the probability distribution of X.Also, find the mean and variance of the distribution.

    Solution

    The first six positive integers are 1, 2, 3, 4, 5, 6.
    We can select the two positive numbers in 6 × 5 = 30 different ways.
    Out of this, 2 numbers are selected at random and let X denote the larger of the two numbers.
    Since X is large of the two numbers, X can assume the value of 2, 3, 4, 5 or 6.
    P (X =2) = P (larger number is 2) = {(1,2) and (2,1)} = 2/1
    P (X = 3) = P (larger number is 3) = {(1,3), (3,1), (2,3), (3,2)} =4/3
    P (X = 4) = P (larger number is 4) = {(1,4), (4,1), (2,4), (4,2), (3,4), (4,3)} = 6/30
    P (X = 5) = P (larger number is 5) = {(1,5), (51,), (2,5), (5,2), (3,5), (5,3), (4,5), (5.4)} = 8/30
    P (X = 6) = P (larger number is 6) = {(1,6), (6,1), (2,6), (6,2), (3,6), (6,3), (4,6), (6,4), (5,6), (6,5)} = 10/30
    Therefore space by space the space above space probability space distribution comma space the space expected space value space or space the space mean space can space be
calculated space as space follows colon
Mean space equals begin inline style sum from space to space of end style space left parenthesis straight X subscript straight i space straight x space straight P space left parenthesis straight X subscript straight i right parenthesis right parenthesis space

equals space 2 space straight x 2 over 30 plus 3 space straight x 4 over 30 space plus space 4 space straight x space 6 over 30 space plus 5 space space straight x space 8 over 30 space plus 6 space straight x 10 over 30 space

equals fraction numerator 4 plus 12 plus 24 plus 40 plus 60 over denominator 30 end fraction space equals 140 over 30 space equals space 14 over 3

     

    Question 240
    CBSEENMA12035659

    Find the distance of a point (2, 5, −3) from the plane straight r with rightwards arrow on top. open parentheses 6 straight i with hat on top minus 3 straight j with hat on top plus 2 straight k with hat on top close parentheses space equals 4.

    Solution

    Consider the vector equation of the plane.
    straight r with rightwards arrow on top. space open parentheses 6 straight i with hat on top minus 3 straight j with hat on top space plus space 2 straight k with hat on top close parentheses space equals space 4
space space space space space rightwards double arrow open parentheses straight x straight i with hat on top space plus space straight y straight j with hat on top space plus space straight z straight k with hat on top close parentheses. space open parentheses 6 straight i with hat on top minus 3 straight j with hat on top space plus space 2 straight k with hat on top close parentheses space equals space 4
space space space space space rightwards double arrow 6 straight x minus 37 plus 2 straight z space equals 4
space space space space space rightwards double arrow 6 straight x minus 3 straight y plus 2 straight z minus 4 space equals space 0 space space space space space
space space
    Thus the Cartesian equation of the plane is
    6x-3y+2z-4 = 0
    Let d be the distance between the point (2, 5, -3)
    Thus space straight d space equals space open vertical bar fraction numerator ax subscript 1 plus by subscript 1 plus cz subscript 1 plus straight d over denominator square root of straight a squared plus straight b squared plus straight c squared end root end fraction close vertical bar
space space space rightwards double arrow straight d space equals space open vertical bar fraction numerator 6 cross times 2 minus 3 cross times 5 plus 2 cross times left parenthesis negative 3 right parenthesis minus 4 over denominator square root of 6 squared plus left parenthesis negative 3 right parenthesis squared plus 2 squared end root end fraction close vertical bar
space space space rightwards double arrow straight d space equals space open vertical bar fraction numerator 12 minus 15 minus 6 minus 4 over denominator square root of 36 plus 9 plus 4 end root end fraction close vertical bar
space space space space rightwards double arrow straight d space equals space open vertical bar fraction numerator negative 13 over denominator square root of 49 end fraction close vertical bar
space space space space rightwards double arrow straight d space equals space 13 over 7 units

    Question 241
    CBSEENMA12035662

    Find the integrating factor for the following differential equation:straight x space log space straight x dy over dx space plus space straight y space equals space 2 logx space

    Solution

    Consider the given differential equation:
    xlogx dy over dx plus straight y space equals space 2 logx
    Dividing the above equation by xlogx, we have, 
    space space fraction numerator xlogx space over denominator xlogx end fraction dy over dx space plus space fraction numerator straight y over denominator straight x space logx end fraction space equals space fraction numerator 2 logx over denominator xlogx end fraction
rightwards double arrow dy over dx plus Py space equals space straight Q comma space where space straight P space and space straight Q space are space functions space of space straight x
Comparing space equation space left parenthesis 1 right parenthesis space and space the space general space equation comma space we space have comma space
straight P left parenthesis straight x right parenthesis space equals space fraction numerator 1 over denominator straight x space logx end fraction space and space straight Q left parenthesis straight x right parenthesis space equals space 2 over straight x
The space intergrating space factor space is space given space by space the space formulae space straight e to the power of integral Pdx end exponent
space Thus comma space straight I. straight F. space equals space straight e to the power of integral Pdx end exponent space space equals space straight e to the power of integral fraction numerator dx over denominator straight x space log space straight x end fraction end exponent
    Consider space straight I space equals space integral dx over xlogx
Substituting space logx equals space straight t semicolon space space dx over straight x space equals space dt
Thus space straight I space equals space integral dt over straight t space equals space log left parenthesis straight t right parenthesis space equals space log space left parenthesis log space straight x right parenthesis
Hence comma space straight I. straight F. equals space straight e to the power of integral fraction numerator dx over denominator straight x space log space straight x end fraction end exponent space equals space straight e to the power of log left parenthesis log space straight x right parenthesis end exponent space equals space log space straight x

    Question 242
    CBSEENMA12035666

    Evaluate: integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin squared straight x over denominator sinx plus cosx end fraction dx.

    Solution
    Let space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin squared straight x over denominator sinx plus cosx end fraction dx space space space... left parenthesis straight i right parenthesis
rightwards double arrow space space space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin squared open parentheses begin display style straight pi over 2 end style minus straight x close parentheses over denominator sin open parentheses begin display style straight pi over 2 end style minus straight x close parentheses plus cos open parentheses begin display style straight pi over 2 end style minus straight x close parentheses end fraction dx space left curly bracket Using space Property space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis dx space equals integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis dx right curly bracket
rightwards double arrow space straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator cos squared straight x over denominator sinx plus cosx end fraction dx.... left parenthesis ii right parenthesis
Adding space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis comma
rightwards double arrow space 2 straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator sin squared straight x plus cos squared straight x over denominator sinx plus cosx end fraction dx
rightwards double arrow space 2 straight I space equals space integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator dx over denominator sinx plus cosx end fraction
rightwards double arrow 2 straight I space equals space fraction numerator 1 over denominator square root of 2 end fraction integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator dx over denominator sinx. begin display style fraction numerator 1 over denominator square root of 2 end fraction end style plus cosx begin display style fraction numerator 1 over denominator square root of 2 end fraction end style end fraction
rightwards double arrow 2 straight I space equals space fraction numerator 1 over denominator square root of 2 end fraction integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator dx over denominator sinx. space cos begin display style straight pi over 4 end style plus cosx. sin begin display style straight pi over 4 end style end fraction
    rightwards double arrow space 2 straight I space equals fraction numerator 1 over denominator square root of 2 end fraction integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator dx over denominator sin open parentheses begin display style straight pi over 4 end style plus straight x close parentheses end fraction
rightwards double arrow space 2 straight I space equals space fraction numerator 1 over denominator square root of 2 end fraction integral subscript 0 superscript straight pi divided by 2 end superscript cosec open parentheses straight pi over 4 plus straight x close parentheses dx
rightwards double arrow space 2 straight I space equals fraction numerator 1 over denominator square root of 2 end fraction open square brackets In open vertical bar cosec open parentheses straight pi over 4 plus straight x close parentheses minus cot open parentheses straight pi over 4 plus straight x close parentheses close vertical bar close square brackets subscript 0 superscript straight pi divided by 2 end superscript
rightwards double arrow space 2 straight I space equals space fraction numerator 1 over denominator square root of 2 end fraction open square brackets ln open vertical bar cosec open parentheses straight pi over 4 plus straight pi over 2 close parentheses minus cot open parentheses straight pi over 4 plus straight pi over 2 close parentheses close vertical bar minus ln open vertical bar cosec open parentheses straight pi over 4 plus 0 close parentheses minus cot open parentheses straight pi over 4 plus 0 close parentheses close vertical bar close square brackets
rightwards double arrow space 2 straight I space equals space fraction numerator 1 over denominator square root of 2 end fraction open square brackets In open vertical bar square root of 2 minus left parenthesis negative 1 right parenthesis close vertical bar minus In open vertical bar square root of 2 minus 1 close vertical bar close square brackets
rightwards double arrow straight I space equals space fraction numerator 1 over denominator 2 square root of 2 end fraction open square brackets In open vertical bar fraction numerator square root of 2 plus 1 over denominator square root of 2 minus 1 end fraction close vertical bar close square brackets
    Question 243
    CBSEENMA12035667

    Evaluate integral subscript negative 1 end subscript superscript 2 left parenthesis straight e to the power of 3 straight x end exponent plus 7 straight x minus 5 right parenthesis dx

    Solution
    integral subscript negative 1 end subscript superscript 2 left parenthesis straight e to the power of 3 straight x end exponent plus 7 straight x minus 5 right parenthesis dx
Here space straight f left parenthesis straight x right parenthesis space equals space straight e to the power of 3 straight x end exponent plus 7 straight x minus 5
straight a space equals negative 1 comma space space straight b equals space 2 comma space space straight h space equals space fraction numerator straight b minus straight a over denominator straight n end fraction equals 3 over straight n
By space definition space integral subscript negative 1 end subscript superscript 2 left parenthesis straight e to the power of 3 straight x end exponent plus 7 straight x minus 5 right parenthesis dx space equals limit as straight n rightwards arrow infinity of sum from straight r equals 1 to straight n of straight h. straight f left parenthesis straight a plus rh right parenthesis
limit as straight n rightwards arrow infinity of sum from straight r equals 1 to straight n of straight h. straight f left parenthesis negative 1 plus rh right parenthesis equals limit as straight n rightwards arrow infinity of sum from straight r equals 1 to straight n of straight h. open parentheses straight e to the power of 3 left parenthesis negative 1 plus rh right parenthesis end exponent plus 7 left parenthesis negative 1 plus rh right parenthesis minus 5 close parentheses
space space space equals space limit as straight n rightwards arrow infinity of open square brackets straight h. straight e to the power of negative 3 end exponent. space straight e to the power of 3 straight h end exponent open parentheses 1 plus straight e to the power of 3 straight h end exponent plus straight e to the power of 6 straight h end exponent plus.. plus straight e to the power of 3 nh end exponent close parentheses plus 7 straight h squared left parenthesis 1 plus 2 plus 3 plus.. plus straight n right parenthesis minus 12 nh close square brackets
space space space equals space limit as straight n rightwards arrow infinity of open square brackets he to the power of 3 straight h end exponent over straight e cubed cross times fraction numerator straight e to the power of 3 nh end exponent minus 1 over denominator straight e to the power of 3 straight h end exponent minus 1 end fraction plus 7 straight h squared fraction numerator straight n left parenthesis straight n plus 1 right parenthesis over denominator 2 end fraction minus 12 nh close square brackets
space space space equals limit as straight n rightwards arrow infinity of open square brackets open parentheses fraction numerator 3 straight e to the power of 3 cross times begin display style 3 over straight n end style end exponent over denominator ne cubed end fraction cross times open parentheses straight e to the power of 3 straight n cross times 3 over straight n minus 1 end exponent close parentheses cross times open parentheses fraction numerator 3 straight h over denominator straight e to the power of 3 straight h end exponent minus 1 end fraction close parentheses cross times fraction numerator straight n over denominator 3 cross times 3 end fraction close parentheses plus 63 over straight n squared cross times fraction numerator straight n left parenthesis straight n plus 1 right parenthesis over denominator 2 end fraction minus 12 cross times 3 close square brackets
    Now applying the limit we get,
    equals fraction numerator straight e to the power of 9 minus 1 over denominator 3 straight e cubed end fraction plus 63 over 2 minus 36
equals fraction numerator straight e to the power of 9 minus 1 over denominator 3 straight e cubed end fraction minus 9 over 2
    Question 244
    CBSEENMA12035668

    Evaluate:
    integral fraction numerator straight x squared over denominator straight x to the power of 4 plus straight x squared minus 2 end fraction dx

    Solution
    integral fraction numerator straight x squared over denominator straight x to the power of 4 plus straight x squared minus 2 end fraction dx
equals integral fraction numerator straight x squared over denominator left parenthesis straight x squared minus 1 right parenthesis thin space left parenthesis straight x squared plus 2 right parenthesis end fraction dx
equals integral fraction numerator straight x squared over denominator left parenthesis straight x minus 1 right parenthesis thin space left parenthesis straight x plus 1 right parenthesis thin space left parenthesis straight x squared plus 2 right parenthesis end fraction dx
Using space partial space fraction comma
space space fraction numerator straight x squared over denominator left parenthesis straight x minus 1 right parenthesis left parenthesis straight x plus 1 right parenthesis thin space left parenthesis straight x squared plus 2 right parenthesis end fraction space equals space fraction numerator straight A over denominator left parenthesis straight x minus 1 right parenthesis end fraction plus fraction numerator straight B over denominator left parenthesis straight x plus 1 right parenthesis end fraction plus fraction numerator Cx plus straight D over denominator left parenthesis straight x squared plus 2 right parenthesis end fraction
fraction numerator straight x squared over denominator left parenthesis straight x minus 1 right parenthesis left parenthesis straight x plus 1 right parenthesis left parenthesis straight x squared plus 2 right parenthesis end fraction equals fraction numerator straight A left parenthesis straight x plus 1 right parenthesis left parenthesis straight x squared plus 2 right parenthesis plus straight B left parenthesis straight x squared plus 2 right parenthesis left parenthesis straight x minus 1 right parenthesis plus left parenthesis Cx plus straight D right parenthesis left parenthesis straight x minus 1 right parenthesis left parenthesis straight x plus 1 right parenthesis over denominator left parenthesis straight x minus 1 right parenthesis left parenthesis straight x plus 1 right parenthesis left parenthesis straight x squared plus 2 right parenthesis end fraction
    Equating the coefficients from both the numerators we get,
     A+B+C = 0 ....(1)
      A-B+D = 1 ....(2)
      2A+2B-C = 0 ...(3)
      2A-2B-D = 0 .....(4)
    Solving the above equations we get,
     straight A equals 1 over 6 comma space space straight B space equals space minus 1 over 6 comma space straight C equals space space 0 comma space straight D space equals space 2 over 3
Our space Intergral space becomes comma
integral fraction numerator straight x squared over denominator left parenthesis straight x minus 1 right parenthesis thin space left parenthesis straight x plus 1 right parenthesis space left parenthesis straight x squared plus 2 right parenthesis end fraction dx space equals space integral fraction numerator 1 over denominator 6 left parenthesis straight x minus 1 right parenthesis end fraction minus fraction numerator 1 over denominator 6 left parenthesis straight x plus 1 right parenthesis end fraction plus fraction numerator 2 over denominator 3 left parenthesis straight x squared plus 2 right parenthesis end fraction dx
equals space 1 over 6 log left parenthesis straight x minus 1 right parenthesis minus 1 over 6 log left parenthesis straight x plus 1 right parenthesis plus 2 over 3 cross times fraction numerator 1 over denominator square root of 2 end fraction tan to the power of negative 1 end exponent open parentheses fraction numerator straight x over denominator square root of 2 end fraction close parentheses plus straight C
equals 1 over 6 open square brackets log left parenthesis straight x minus 1 right parenthesis minus log left parenthesis straight x plus 1 right parenthesis plus 2 square root of 2 tan to the power of negative 1 end exponent open parentheses fraction numerator straight x over denominator square root of 2 end fraction close parentheses close square brackets plus straight C
    Question 245
    CBSEENMA12035669

    In a set of 10 coins, 2 coins are with heads on both the sides. A coin is selected at random from this set and tossed five times. If all the five times, the result was heads, find the probability that the selected coin had heads on both the sides

    Solution

    Let E1  E1 and A be the events defined as follows:
    E1 = Selecting a coin having head on both the sides
    E1= Selecting a coin not having head on both the sides
    A = Getting all heads when a coin is tossed five times
    We have to find P(E1/A).
    There are 2 coins having heads on both the sides.
    straight P left parenthesis straight E subscript 1 right parenthesis space equals space fraction numerator straight C presuperscript 2 subscript 1 over denominator straight C presuperscript 10 subscript 1 end fraction equals space 2 over 10
    There are 8 coins not having heads on both the sides.
    straight P left parenthesis straight E subscript 2 right parenthesis equals space fraction numerator straight C presuperscript 8 subscript 1 over denominator straight C presuperscript 10 subscript 1 end fraction space equals 8 over 10
straight P left parenthesis straight A divided by straight E subscript 1 right parenthesis space equals space left parenthesis 1 right parenthesis to the power of 5 space equals space 1
straight P left parenthesis straight A divided by straight E subscript 2 right parenthesis space equals space open parentheses 1 half close parentheses to the power of 5
    By Baye's Theorem, we have
    straight P left parenthesis straight E subscript 1 divided by straight A right parenthesis space equals space fraction numerator straight P left parenthesis straight E subscript 1 right parenthesis thin space straight P left parenthesis straight A divided by straight E subscript 1 right parenthesis over denominator straight P left parenthesis straight E subscript 1 right parenthesis thin space straight P left parenthesis straight A divided by straight E subscript 1 right parenthesis plus space straight P left parenthesis straight E subscript 2 right parenthesis thin space straight P left parenthesis straight A divided by straight E subscript 2 right parenthesis end fraction
space space space space space space equals space fraction numerator open parentheses begin display style 2 over 10 end style close parentheses left parenthesis 1 right parenthesis over denominator open parentheses begin display style 2 over 10 end style close parentheses left parenthesis 1 right parenthesis plus open parentheses begin display style 8 over 10 end style close parentheses open parentheses begin display style 1 half end style close parentheses to the power of 5 end fraction
space space space space space space space equals space fraction numerator 2 over denominator 2 plus open parentheses begin display style 8 over 32 end style close parentheses end fraction equals space 8 over 9

    Question 246
    CBSEENMA12035670

    How many times must a fair coin be tossed so that the probability of getting at least one head is more than 80%?

    Solution

    Let  p denotes the probability of getting heads.
    Let q denotes the probability of getting tails.
    straight p space equals space 1 half
straight q space equals space 1 minus 1 half space equals 1 half
    Suppose the coin is tossed n times.
    Let X denote the number of times of getting heads in n trails. 
    straight P left parenthesis straight X equals straight r right parenthesis space equals space straight C presuperscript straight n subscript straight r straight p to the power of straight r straight q to the power of straight n minus straight r end exponent space equals space straight C presuperscript straight n subscript straight r open parentheses 1 half close parentheses to the power of straight r open parentheses 1 half close parentheses to the power of straight n minus straight r end exponent space equals straight C presuperscript straight n subscript straight r open parentheses 1 half close parentheses to the power of straight n comma space space straight r space equals space 0 comma 1 comma space 2... comma straight n
straight P left parenthesis straight X greater or equal than 1 right parenthesis greater than 80 over 100
rightwards double arrow space space straight P left parenthesis straight X equals 1 right parenthesis plus straight P left parenthesis straight X equals 2 right parenthesis plus..... plus left parenthesis straight X equals straight n right parenthesis greater than 80 over 1000
rightwards double arrow space straight P left parenthesis straight X equals 1 right parenthesis plus straight P left parenthesis straight X equals 2 right parenthesis plus.... plus straight P left parenthesis straight X equals straight n right parenthesis plus straight P left parenthesis straight X equals 0 right parenthesis minus straight P left parenthesis straight X equals 0 right parenthesis greater than 80 over 100
rightwards double arrow 1 minus straight P left parenthesis straight X equals 0 right parenthesis greater than 80 over 100
rightwards double arrow straight P left parenthesis straight X equals 0 right parenthesis space less than 1 fifth
rightwards double arrow straight C presuperscript straight n subscript 0 open parentheses 1 half close parentheses to the power of straight n less than 1 fifth
rightwards double arrow open parentheses 1 half close parentheses to the power of straight n less than 1 fifth
rightwards double arrow straight n space equals space 3 comma 4 comma 5......
    So the fair coin should be tossed for 3 or more times for getting the required probability.

    Question 247
    CBSEENMA12035671
    Question 248
    CBSEENMA12035672

    A line passing through the point A with position vector straight a with rightwards arrow on top space equals space 4 straight i with hat on top plus 2 straight j with hat on top plus 2 straight k with hat on top is parallel to the vector straight b with rightwards arrow on top space equals space 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top. Find the length of the perpendicular drawn on this line from a point p with vector stack straight r subscript 1 with rightwards arrow on top space equals straight i with hat on top plus 2 straight j with hat on top plus 3 straight k with hat on top.

    Solution

    Let the equation of the line be straight r with rightwards arrow on top space equals space straight a with rightwards arrow on top space plus space straight lambda straight b with rightwards arrow on top
     Here comma space straight a with rightwards arrow on top space equals space 4 straight i with hat on top plus 2 straight j with hat on top plus 2 straight k with hat on top
straight b with rightwards arrow on top equals space 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top
therefore space Equation space of space the space line space is space straight r with rightwards arrow on top space equals space 4 straight i with hat on top plus 2 straight j with hat on top plus 2 straight k with hat on top plus bold lambda left parenthesis 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top right parenthesis
Let space straight L space be space the space foot space of space the space perpendicular space and space straight P space be space the space required space point space from
which space we space have space to space find space the space length space of space the space perpendicular
straight P open parentheses straight alpha with rightwards arrow on top close parentheses space equals straight i with hat on top plus 2 straight j with hat on top plus 3 straight k with hat on top
PL with rightwards arrow on top space equals space Position space of space vector space of space straight L space minus space Position space vector space of space straight P
space space space space space space equals 4 straight i with hat on top plus 2 straight j with hat on top plus 2 straight k with hat on top plus straight lambda open parentheses 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top close parentheses minus open parentheses straight i with hat on top plus 2 straight j with hat on top plus 3 straight k with hat on top close parentheses
space space space space space space equals 3 straight i with hat on top minus straight k with hat on top plus straight lambda open parentheses 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top close parentheses space.... left parenthesis straight i right parenthesis
    Now 
    PL with rightwards arrow on top. space straight b with rightwards arrow on top space equals space 0 left square bracket Since space PL with rightwards arrow on top space is space perpendicular space to space straight b with rightwards arrow on top right square bracket
space space open square brackets 3 straight i with hat on top minus straight k with hat on top plus straight lambda open parentheses 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top close parentheses close square brackets. space open parentheses 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top close parentheses equals 0
space rightwards double arrow open square brackets straight i with hat on top left parenthesis 3 plus 2 straight lambda right parenthesis plus straight j with hat on top left parenthesis 3 straight lambda right parenthesis plus space straight k with hat on top left parenthesis negative 1 plus 6 straight lambda right parenthesis close square brackets. space open parentheses 2 straight i with hat on top plus 3 straight j with hat on top plus 6 straight k with hat on top close parentheses space equals space 0
space rightwards double arrow left parenthesis 3 plus 2 straight lambda right parenthesis 2 plus left parenthesis 3 straight lambda right parenthesis 3 plus left parenthesis negative 1 plus 6 straight lambda right parenthesis 6 space equals space 0
space space rightwards double arrow 6 plus 4 straight lambda plus 9 straight lambda minus 6 plus 36 straight lambda space equals space 0
space space space rightwards double arrow 49 straight lambda space equals space 0
space space space space space therefore space space straight lambda space equals space 0
space space PL with rightwards arrow on top equals 3 straight i with hat on top minus straight k with hat on top space left square bracket from space left parenthesis ii right parenthesis right square bracket
space space open vertical bar PL with rightwards arrow on top close vertical bar space equals open vertical bar square root of 3 squared plus left parenthesis negative 1 right parenthesis squared end root close vertical bar
space space therefore space space open vertical bar PL with rightwards arrow on top close vertical bar space equals space square root of 10


space space space space space
    Length of the perpendicular drawn on the line from P = square root of 10

    Question 249
    CBSEENMA12035678

    Evaluate: integral fraction numerator left parenthesis straight x plus 3 right parenthesis straight e to the power of straight x over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction dx

    Solution
    integral fraction numerator left parenthesis straight x plus 3 right parenthesis straight e to the power of straight x over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction dx
space equals integral fraction numerator left parenthesis straight x plus 5 minus 2 right parenthesis straight e to the power of straight x over denominator left parenthesis straight x plus 5 right parenthesis end fraction dx
equals integral open square brackets fraction numerator left parenthesis straight x plus 5 right parenthesis over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction minus fraction numerator 2 over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction close square brackets straight e to the power of straight x dx
space equals integral open square brackets fraction numerator 1 over denominator left parenthesis straight x plus 5 right parenthesis squared end fraction minus fraction numerator 2 over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction close square brackets straight e to the power of straight x dx
space This space is space of space the space form
space integral straight e to the power of straight x left square bracket straight f left parenthesis straight x right parenthesis plus straight f apostrophe left parenthesis straight x right parenthesis right square bracket dx space equals space straight e to the power of straight x straight f left parenthesis straight x right parenthesis plus straight C
space space rightwards double arrow space space space integral open square brackets fraction numerator 1 over denominator left parenthesis straight x plus 5 right parenthesis squared end fraction minus fraction numerator 2 over denominator left parenthesis straight x plus 5 right parenthesis cubed end fraction close square brackets straight e to the power of straight x dx
space space space space space equals space fraction numerator straight e to the power of straight x over denominator left parenthesis straight x plus 5 right parenthesis squared end fraction plus straight C
    Question 251
    CBSEENMA12035686

    Show that lines:
    straight r with rightwards arrow on top space equals space straight i with hat on top space plus straight j with hat on top space plus straight k with hat on top space plus space straight lambda open parentheses straight i with hat on top minus straight j with hat on top space plus space straight k with hat on top close parentheses
straight r with rightwards arrow on top space equals space 4 straight j with hat on top space plus space 2 straight k with hat on top space plus space straight mu open parentheses 2 straight j with hat on top minus straight j with hat on top plus 3 straight k with hat on top close parentheses space are space coplanar.
    Also, find the equation of the plane containing these lines. 

    Solution
    straight r with rightwards arrow on top space equals space straight i with hat on top space plus space straight j with hat on top space plus space straight k with hat on top space plus space straight lambda left parenthesis straight i with hat on top minus straight j with hat on top plus straight k with hat on top right parenthesis space... left parenthesis straight i right parenthesis
    Converting into cartesian form,
    fraction numerator straight x minus 1 over denominator 1 end fraction space equals fraction numerator straight y minus 1 over denominator negative 1 end fraction equals fraction numerator straight z minus 1 over denominator 1 end fraction
left parenthesis straight x subscript 1 comma space straight y subscript 1 comma space straight z subscript 1 right parenthesis space equals space left parenthesis 1 comma space 1 comma space 1 right parenthesis
straight a subscript 1 space equals space 1 comma space space straight b subscript 1 space equals negative 1 comma space space straight c subscript 1 space equals 1
    straight r with rightwards arrow on top equals 4 straight j with hat on top plus 2 straight k with hat on top plus straight mu left parenthesis 2 straight i with hat on top minus straight j with hat on top plus 3 straight k with hat on top right parenthesis space space space... left parenthesis ii right parenthesis 
    Converting into cartesian form,
    fraction numerator straight x minus 0 over denominator 2 end fraction equals fraction numerator straight y minus 4 over denominator negative 1 end fraction equals fraction numerator straight z minus 2 over denominator 3 end fraction
left parenthesis straight x subscript 2 comma space straight y subscript 2 comma space straight z subscript 2 right parenthesis space equals space left parenthesis 0 comma space 4 comma space 2 right parenthesis
straight a subscript 2 equals space 2 comma space space straight b subscript 2 equals negative 1 comma space space straight c subscript 2 equals 3
    Condition for the lines to be coplanar is
    open vertical bar table row cell 0 minus 1 end cell cell space 4 minus 1 end cell cell space 2 minus 1 end cell row 1 cell negative 1 end cell 1 row 2 cell negative 1 end cell 3 end table close vertical bar space equals space open vertical bar table row cell negative 1 end cell cell space space 3 end cell cell space space 1 end cell row 1 cell negative 1 end cell cell space space 1 end cell row 2 cell negative 1 end cell cell space space 3 end cell end table close vertical bar equals 0
    therefore space the space lines space are space coplanar.
Intersection space of space the space two space lines space is
Let space the space equation space be space straight a left parenthesis straight x minus straight x subscript 1 right parenthesis plus straight b left parenthesis straight y minus straight y subscript 1 right parenthesis plus straight c left parenthesis straight z minus straight z subscript 1 right parenthesis space equals space 0 space... left parenthesis iii right parenthesis
Direction space ratios space of space the space plane space is
straight a minus straight b plus straight c equals 0
2 straight a minus straight b plus 3 straight c space equals 0
Solving space by space cross minus multiplication comma
fraction numerator straight a over denominator negative 3 plus 1 end fraction equals fraction numerator straight b over denominator 2 minus 3 end fraction equals fraction numerator straight c over denominator negative 1 plus 2 end fraction
straight a equals negative 2 straight lambda comma space space straight b equals negative straight lambda comma space space straight c equals straight lambda
    Since the plane passes through (0, 4, 2) from line (ii)
    straight a left parenthesis straight x minus 0 right parenthesis plus straight b left parenthesis straight y minus 4 right parenthesis plus straight c left parenthesis straight z minus 2 right parenthesis space equals 0
rightwards double arrow space minus 2 λx minus straight lambda left parenthesis straight y minus 4 right parenthesis plus straight lambda left parenthesis straight z minus 2 right parenthesis space equals 0
rightwards double arrow space minus 2 straight x minus straight y plus 4 plus straight z minus 2 equals 0
rightwards double arrow negative 2 straight x minus straight y plus straight z equals negative 2
rightwards double arrow 2 straight x plus straight y minus straight z equals 2
    Question 252
    CBSEENMA12035688

    Two the numbers are selected at random (without replacement) from first six positive integers. Let X denote the larger of the two numbers obtained. Find the probability distribution of X. Find the mean and variance of this distribution.

    Solution

    First six positive integers are {1, 2, 3, 4, 5, 6}
    No. of ways of selecting 2 numbers from 6 numbers without replacement = space straight C presuperscript 6 subscript 2 space equals 15 
    X denotes the larger of the two numbers, so X can take the values 2, 3, 4, 5, 6.
    Probability distribution of X:

    X 2 3 4 5 6
    P(x) 1/15 2/15 3/15 4/15 5/15

    Computation of Mean and Variance:
    xi P(X=xi) space straight p subscript straight i straight x subscript straight i
    space straight p subscript straight i straight x subscript straight i superscript 2
    2 1/15 2/15 4/15
    3 2/15 6/15 18/15
    4 3/15 12/15 48/15
    5 4/15 20/15 100/15
    6 5/15 30/15 180/15
        space sum from blank to blank of straight p subscript straight i straight x subscript straight i space equals space 70 over 15 equals 14 over 3 space sum from blank to blank of pix subscript straight i superscript 2 space equals space 350 over 15 equals 70 over 3

    space Mean equals sum from blank to blank of straight p subscript straight i straight x subscript straight i space equals space 70 over 15 space equals space 4.67
Variance equals space sum from blank to blank of straight p subscript straight i straight x subscript straight i squared space minus left parenthesis sum from blank to blank of straight p subscript straight i straight x subscript straight i right parenthesis squared space equals 70 over 3 minus 196 over 9 equals fraction numerator 210 minus 196 over denominator 9 end fraction equals 14 over 9
    Question 253
    CBSEENMA12035693

    If space straight f left parenthesis straight x right parenthesis space equals space integral subscript 0 superscript straight x straight t space sint space dt comma space write space the space value space of space straight f apostrophe left parenthesis straight x right parenthesis

    Solution

    Since differentiation operation is the inverse operation of integration, we have
    straight f apostrophe left parenthesis straight x right parenthesis space equals space straight x space sinx
Let space straight f left parenthesis straight x right parenthesis space equals space integral subscript 0 superscript straight x straight t space sint space dt
    Let us do this by integration by parts. 
    Therefore assume u = t; du = dt
    integral sint space dt space space equals space integral dv
minus cost space equals straight v
Therefore comma space
straight f left parenthesis straight x right parenthesis space equals space open square brackets straight t left parenthesis negative cost right parenthesis close square brackets subscript 0 superscript straight x space minus space integral subscript 0 superscript straight x left parenthesis negative cos space straight t right parenthesis space dt
straight f left parenthesis straight x right parenthesis space equals space minus straight x space cosx space plus space sinx space plus straight C
    Differentiating the above function with respect to x,
    straight f apostrophe left parenthesis straight x right parenthesis space equals space minus open square brackets straight x left parenthesis negative sinx right parenthesis minus sinx close square brackets space plus space sinx space equals space straight x space sinx

    Question 254
    CBSEENMA12035697

    If integral subscript 0 superscript straight a fraction numerator 1 over denominator 4 plus straight x squared end fraction dx equals straight pi over 8, find the value of a.

    Solution
    bold Given bold space bold that integral subscript 0 superscript straight a fraction numerator dx over denominator 4 plus straight x squared end fraction equals straight pi over 8
We space need space to space find space the space value space of space straight a.
Let space straight I space equals space integral subscript 0 superscript straight a fraction numerator dx over denominator 4 plus straight x squared end fraction equals space straight pi over 8
Thus comma space straight I space equals space 1 half open parentheses tan to the power of negative 1 end exponent straight x over 2 close parentheses subscript 0 superscript straight a equals space space straight pi over 8
rightwards double arrow 1 half tan to the power of negative 1 end exponent straight a over 2 equals straight pi over 8
rightwards double arrow tan to the power of negative 1 end exponent straight a over 2 equals 2 cross times straight pi over 8
rightwards double arrow tan to the power of negative 1 end exponent straight a over 2 equals straight pi over 4
rightwards double arrow straight a over 2 equals 1
rightwards double arrow straight a equals 2
    Question 255
    CBSEENMA12035702

    Evaluate colon
integral subscript 0 superscript straight pi fraction numerator 4 straight x space sinx over denominator 1 plus cos squared straight x end fraction dx

    Solution

    We need to evaluate the integral
    straight I space equals space integral subscript 0 superscript straight pi fraction numerator 4 straight x space sinx over denominator 1 plus cos squared straight x end fraction dx... left parenthesis 1 right parenthesis
Using space the space property space integral straight f left parenthesis straight a minus straight x right parenthesis dx equals integral straight f left parenthesis straight x right parenthesis dx comma space we space have
straight I equals space integral subscript 0 superscript straight pi fraction numerator 4 left parenthesis straight pi minus straight x right parenthesis space sin left parenthesis straight pi minus straight x right parenthesis over denominator 1 plus cos squared left parenthesis straight pi minus straight x right parenthesis end fraction dx
rightwards double arrow space space straight I space equals space integral subscript 0 superscript straight pi fraction numerator 4 straight pi space sinx over denominator 1 plus cos squared straight x end fraction dx minus integral subscript 0 superscript straight pi fraction numerator 4 straight x space sinx over denominator 1 plus cos squared straight x end fraction dx... left parenthesis 2 right parenthesis
Adding space equations space left parenthesis 1 right parenthesis space and space left parenthesis 2 right parenthesis comma space we space have comma
    rightwards double arrow 2 straight I space equals space integral subscript 0 superscript straight pi fraction numerator 4 straight x space sinx over denominator 1 plus cos squared straight x end fraction dx space plus space integral subscript 0 superscript straight pi fraction numerator 4 πsinx over denominator 1 plus cos squared straight x end fraction dx minus integral subscript 0 superscript straight pi fraction numerator 4 straight x space sinx over denominator 1 plus cos squared straight x end fraction dx
rightwards double arrow 2 straight I space equals space integral subscript 0 superscript straight pi fraction numerator 4 straight pi space sinx over denominator 1 plus cos squared straight x end fraction dx
rightwards double arrow 2 straight I space equals space 4 straight pi integral subscript 0 superscript straight pi fraction numerator sinx over denominator 1 plus cos squared straight x end fraction dx
    Substitute space straight t space equals space cosx semicolon space dt space equals space minus sinxdx
when space straight x space equals space 0 comma space space straight t space equals 1
when space straight x space equals space straight pi comma space straight t equals negative 1
rightwards double arrow 2 straight I space equals space 4 straight pi integral subscript 1 superscript negative 1 end superscript fraction numerator left parenthesis negative 1 right parenthesis dt over denominator 1 plus straight t squared end fraction
rightwards double arrow space straight I space equals space 2 straight pi integral subscript negative 1 end subscript superscript 1 space fraction numerator dt over denominator 1 plus straight t squared end fraction
rightwards double arrow straight I space equals 2 cross times 2 straight pi integral subscript 0 superscript 1 fraction numerator dt over denominator 1 plus straight t squared end fraction
rightwards double arrow straight I space equals space 2 cross times 2 straight pi open parentheses tan to the power of negative 1 end exponent straight t close parentheses subscript 0 superscript 1
rightwards double arrow space straight I equals space 4 straight pi space tan to the power of negative 1 end exponent left parenthesis 1 right parenthesis
rightwards double arrow space straight I equals 4 straight pi cross times straight pi over 4 equals straight pi squared

    Question 256
    CBSEENMA12035703

    Evaluate:
    integral fraction numerator straight x plus 2 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx

    Solution

    We need to evaluate the integral
    integral fraction numerator straight x plus 2 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
Let space straight I space equals space integral fraction numerator straight x plus 2 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
Consider space the space integral space as space follows colon
fraction numerator straight x plus 2 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction space equals fraction numerator straight A begin display style straight d over dx end style left parenthesis straight x squared plus 5 straight x plus 6 right parenthesis plus straight B over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction
rightwards double arrow straight x plus 2 space equals space straight A left parenthesis 2 straight x plus 5 right parenthesis plus straight B
rightwards double arrow straight x plus 2 equals left parenthesis 2 straight A right parenthesis straight x plus 5 straight A plus straight B
    Comparing the coefficients, we have
    2A = 1;  5A+B = 2
    Solving the above equations, we have
    straight A equals 1 half space and space straight B equals space minus 1 half
Thus comma space
straight I space equals space integral fraction numerator straight x plus 2 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
space space equals space integral fraction numerator begin display style fraction numerator 2 straight x plus 5 over denominator 2 end fraction end style minus begin display style 1 half end style over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
space space equals 1 half integral fraction numerator 2 straight x plus 5 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx minus 1 half integral fraction numerator 1 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
straight I space equals 1 half straight I subscript 1 space minus space 1 half straight I subscript 2 comma
where space straight I subscript 1 space equals integral fraction numerator 2 straight x plus 5 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
    and space straight I subscript 2 equals space integral fraction numerator 1 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
Now space consider space straight I subscript 1 colon
straight I subscript 1 space equals space integral fraction numerator 2 straight x plus 5 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
Susbstitute
straight x squared plus 5 straight x plus 6 space equals straight t semicolon space left parenthesis 2 straight x plus 5 right parenthesis dx space equals space dt
straight I subscript 1 space equals integral fraction numerator dt over denominator square root of straight t end fraction space equals 2 square root of straight t
equals 2 square root of straight x squared plus 5 straight x plus 6 end root
    Now consider I2:
    straight I subscript 2 space equals space integral fraction numerator 1 over denominator square root of straight x squared plus 5 straight x plus 6 end root end fraction dx
equals space integral fraction numerator 1 over denominator square root of straight x squared plus 5 straight x plus open parentheses begin display style 5 over 2 end style close parentheses squared plus 6 minus open parentheses begin display style 5 over 2 end style close parentheses squared end root end fraction dx
equals integral fraction numerator 1 over denominator square root of open parentheses straight x plus begin display style 5 over 2 end style close parentheses squared plus 6 minus begin display style 25 over 4 end style end root end fraction dx
equals space integral fraction numerator 1 over denominator square root of open parentheses straight x plus begin display style 5 over 2 end style close parentheses squared minus begin display style 1 fourth end style end root end fraction dx
straight I subscript 2 space equals log open vertical bar straight x plus 5 over 2 minus square root of straight x squared plus 5 straight x plus 6 end root close vertical bar plus straight C
Thus comma space straight I equals 1 half straight I subscript 1 minus 1 half straight I subscript 2
straight I space equals space square root of straight x squared plus 5 straight x plus 6 end root minus 1 half log open vertical bar straight x plus 5 over 2 minus square root of straight x squared plus 5 straight x plus 6 end root close vertical bar plus straight C

    Question 257
    CBSEENMA12035723

    Evaluate:
    integral fraction numerator 1 over denominator sin to the power of 4 straight x plus sin squared xcos squared straight x plus cos to the power of 4 straight x end fraction dx

    Solution

    We need to evaluate integral fraction numerator dx over denominator sin to the power of 4 straight x plus sin squared xcos squared straight x plus cos to the power of 4 straight x end fraction
    Let space straight I space equals integral fraction numerator dx over denominator sin to the power of 4 straight x plus sin squared xcos squared straight x plus cos to the power of 4 straight x end fraction
    Multiply the numerator and the denominator by sec to the power of 4 straight x, we have
    straight I space equals space integral fraction numerator sec to the power of 4 xdx over denominator tan to the power of 4 straight x plus tan squared straight x plus 1 end fraction
straight I space equals space integral fraction numerator sec squared straight x cross times sec squared xdx over denominator tan to the power of 4 straight x plus tan squared straight x plus 1 end fraction
Now space substitute space straight t space equals space tanx semicolon space dt space equals space sec squared xdx
Therefore comma space
straight I space equals space integral fraction numerator left parenthesis 1 plus straight t squared right parenthesis dt over denominator straight t to the power of 4 plus straight t squared plus 1 end fraction
straight I space equals space integral fraction numerator open parentheses 1 plus begin display style 1 over straight t squared end style close parentheses dt over denominator open parentheses straight t squared plus begin display style 1 over straight t squared end style plus 1 close parentheses end fraction
straight I space equals integral fraction numerator open parentheses 1 plus begin display style 1 over straight t squared end style close parentheses dt over denominator open parentheses straight t squared plus begin display style 1 over straight t squared end style minus 2 plus 2 plus 1 close parentheses end fraction
straight I space equals space integral fraction numerator open parentheses 1 plus begin display style 1 over straight t squared end style close parentheses dt over denominator open parentheses straight t minus begin display style 1 over straight t end style close parentheses squared plus 3 end fraction
     Substitute space straight z equals straight t minus 1 over straight t semicolon space space dz space equals space open parentheses 1 plus 1 over straight t squared close parentheses dt
straight I space equals space integral fraction numerator dz over denominator straight z squared plus 3 end fraction
straight I space equals space integral fraction numerator dz over denominator straight z squared plus open parentheses square root of 3 close parentheses squared end fraction
straight I space equals fraction numerator 1 over denominator square root of 3 end fraction tan to the power of negative 1 end exponent open parentheses fraction numerator straight z over denominator square root of 3 end fraction close parentheses plus straight c
straight I space equals fraction numerator 1 over denominator square root of 3 end fraction tan to the power of negative 1 end exponent open parentheses fraction numerator straight t minus begin display style 1 over straight t end style over denominator square root of 3 end fraction close parentheses plus straight c
    straight I equals space fraction numerator 1 over denominator square root of 3 end fraction tan to the power of negative 1 end exponent open parentheses fraction numerator tanx minus begin display style 1 over tanx end style over denominator square root of 3 end fraction close parentheses plus straight c
straight I space equals fraction numerator 1 over denominator square root of 3 end fraction tan to the power of negative 1 end exponent open parentheses fraction numerator tanx minus cotx over denominator square root of 3 end fraction close parentheses plus straight c

    Question 258
    CBSEENMA12035742

    Evaluate: integral fraction numerator sin left parenthesis straight x minus straight a right parenthesis over denominator sin left parenthesis straight x plus straight a right parenthesis end fraction dx

    Solution
    straight I space equals space integral fraction numerator sin left parenthesis straight x minus straight a right parenthesis over denominator sin left parenthesis straight x plus straight a right parenthesis 1 end fraction dx
    Let space left parenthesis straight x plus straight a right parenthesis space equals space straight t space rightwards double arrow space dx space equals space dt
therefore space straight I space equals space integral fraction numerator sin left parenthesis straight t minus 2 straight a right parenthesis over denominator sint end fraction dt
equals space integral fraction numerator sint space cos 2 straight a minus cost space sin 2 straight a over denominator sin space straight t end fraction dt
equals integral left parenthesis cos 2 straight a minus cot space straight t space sin 2 straight a right parenthesis space dt
equals left parenthesis cos 2 straight a right parenthesis straight t minus sin 2 straight a space log open vertical bar sin space straight t close vertical bar plus straight C
equals cos 2 straight a left parenthesis straight x plus straight a right parenthesis minus sin 2 straight a space log open vertical bar sin left parenthesis straight x plus straight a right parenthesis close vertical bar plus straight C
    Question 259
    CBSEENMA12035743

    Evaluate:
    integral fraction numerator 5 straight x minus 2 over denominator left parenthesis 1 plus 2 straight x plus 3 straight x squared end fraction dx

    Solution
    integral fraction numerator 5 straight x minus 2 over denominator 1 plus 2 straight x plus 3 straight x squared end fraction dx
equals 5 integral fraction numerator straight x minus begin display style 2 over 5 end style over denominator 1 plus 2 straight x plus 3 straight x squared end fraction dx
equals 5 over 6 integral fraction numerator 6 straight x minus begin display style 12 over 5 end style over denominator 1 plus 2 straight x plus 3 straight x squared end fraction dx
equals 5 over 6 integral fraction numerator 6 straight x plus 2 minus begin display style 12 over 5 end style minus 2 over denominator 1 plus 2 straight x plus 3 straight x squared end fraction dx
equals 5 over 6 integral fraction numerator 6 straight x plus 2 minus begin display style 22 over 5 end style over denominator 1 plus 2 straight x plus 3 straight x squared end fraction dx
equals 5 over 6 integral fraction numerator 6 straight x plus 2 over denominator 1 plus 2 straight x plus 3 straight x squared end fraction dx minus 5 over 6 cross times 22 over 5 integral fraction numerator 1 over denominator 3 open curly brackets open parentheses straight x plus begin display style 1 third end style close parentheses squared plus begin display style 2 over 9 end style close curly brackets end fraction dx
    equals 5 over 6 log open vertical bar 1 plus 2 straight x plus 3 straight x squared close vertical bar minus 11 over 9 integral fraction numerator 1 over denominator open parentheses straight x plus begin display style 1 third end style close parentheses squared plus begin display style 2 over 9 end style end fraction dx
equals 5 over 6 log open vertical bar 1 plus 2 straight x plus 3 straight x squared close vertical bar minus 11 over 9 cross times fraction numerator 3 over denominator square root of 2 end fraction tan to the power of negative 1 end exponent fraction numerator open parentheses straight x plus begin display style 1 third end style close parentheses over denominator begin display style fraction numerator square root of 2 over denominator 3 end fraction end style end fraction plus straight C
equals 5 over 6 log open vertical bar 1 plus 2 straight x plus 3 straight x squared close vertical bar minus fraction numerator 11 over denominator 3 square root of 2 end fraction cross times tan to the power of negative 1 end exponent open parentheses fraction numerator 3 straight x plus 1 over denominator square root of 2 end fraction close parentheses plus straight C
    Question 260
    CBSEENMA12035744

    Evaluate:
    integral fraction numerator straight x squared over denominator left parenthesis straight x squared plus 4 right parenthesis left parenthesis straight x squared plus 9 right parenthesis end fraction dx


    Solution
    Let space straight x squared equals straight y
fraction numerator straight x squared over denominator open parentheses straight x squared plus 4 close parentheses space left parenthesis straight x squared plus 9 right parenthesis end fraction space equals space fraction numerator straight y over denominator left parenthesis straight y plus 4 right parenthesis left parenthesis straight y plus 9 right parenthesis end fraction equals fraction numerator straight A over denominator straight y plus 4 end fraction plus fraction numerator straight B over denominator straight y plus 9 end fraction
straight y space equals space straight A left parenthesis straight y plus 9 right parenthesis plus straight B left parenthesis straight y plus 4 right parenthesis
Comparing space both space sides comma
straight A plus straight B equals 1 space and space 9 straight A plus 4 straight B space equals space 0
Solving comma space We space get space straight A equals fraction numerator negative 4 over denominator 5 end fraction space and space straight B space equals 9 over 5
therefore space space straight I space equals space integral open square brackets fraction numerator negative 4 over denominator 5 left parenthesis straight x squared plus 4 right parenthesis end fraction plus fraction numerator 9 over denominator 5 left parenthesis straight x squared plus 9 right parenthesis end fraction close square brackets dx
space space space space space equals negative 4 over 5 cross times 1 half tan to the power of negative 1 end exponent open parentheses straight x over 2 close parentheses plus 9 over 5 cross times 1 third tan to the power of negative 1 end exponent open parentheses straight x over 3 close parentheses plus straight C
space space space space space equals negative 2 over 5 tan to the power of negative 1 end exponent straight x over 2 plus 3 over 5 tan to the power of negative 1 end exponent straight x over 3 plus straight C
    Question 261
    CBSEENMA12035745

    Evaluate: integral subscript 0 superscript 4 open parentheses open vertical bar straight x close vertical bar plus open vertical bar straight x minus 2 close vertical bar plus open vertical bar straight x minus 4 close vertical bar close parentheses dx

    Solution
    integral subscript 0 superscript 4 open square brackets open vertical bar straight x close vertical bar plus open vertical bar straight x minus 2 close vertical bar plus open vertical bar straight x minus 4 close vertical bar close square brackets dx
equals integral subscript 0 superscript 2 straight f left parenthesis straight x right parenthesis dx plus integral subscript 2 superscript 4 straight f left parenthesis straight x right parenthesis dx
equals integral subscript 0 superscript 2 left parenthesis straight x minus straight x plus 2 minus straight x plus 4 right parenthesis dx plus integral subscript 2 superscript 4 left parenthesis straight x plus straight x minus 2 minus straight x plus 4 right parenthesis dx
equals integral subscript 0 superscript 2 left parenthesis 6 minus straight x right parenthesis dx plus integral subscript 2 superscript 4 left parenthesis straight x plus 2 right parenthesis dx
equals open square brackets 6 straight x minus straight x squared over 2 close square brackets subscript 0 superscript 2 plus open square brackets straight x squared over 2 plus 2 straight x close square brackets subscript 2 superscript 4
equals open square brackets 12 minus 2 close square brackets plus open square brackets 8 plus 8 minus 2 minus 4 close square brackets equals 20
    Question 262
    CBSEENMA12035761

    Evaluate: integral subscript 2 superscript 3 space 3 to the power of straight x space dx.

    Solution
    straight I space equals space integral subscript 2 superscript 3 3 to the power of straight x
space equals space fraction numerator 3 to the power of straight x over denominator log space 3 end fraction vertical line subscript 2 superscript 3 space plus space straight C space
open parentheses Use colon space integral straight a to the power of straight x space equals space fraction numerator straight a to the power of straight x over denominator log space straight a end fraction space plus space straight C close parentheses
space equals space 3 cubed over log minus fraction numerator 3 squared over denominator log space 3 end fraction space plus straight C
equals space 1 over log cubed left parenthesis 3 cubed minus 3 squared right parenthesis space plus space straight C
equals space 1 over log cubed left parenthesis 27 minus 9 right parenthesis space plus space straight C
equals 1 over log cubed left parenthesis 18 right parenthesis space plus space straight C
    Question 263
    CBSEENMA12035767

    Find the vector equation of the line passing through the point A(1, 2, –1) and parallel to the line 5x – 25 = 14 – 7y = 35z.

    Solution

    The equation of the line 5x-25 =14-7y =35z can be rewritten as
    fraction numerator straight x minus 5 over denominator 1 end fraction space equals space fraction numerator straight y minus 2 over denominator negative 1 end fraction space equals fraction numerator straight z over denominator 1 divided by 35 end fraction
rightwards double arrow fraction numerator straight x minus 5 over denominator 7 end fraction space equals space fraction numerator straight y minus 2 over denominator negative 5 end fraction space equals straight z over 1
    Since the required line is parallel to the given line, so the direction ratio of the required line is proportional to 7,-5,1
    The vector equation of the required line passing through the point (1,2-1) and having direction ratios proportional to 7,-5 1 is
    straight r with rightwards arrow on top space equals space left parenthesis straight i with hat on top space plus 2 straight j with hat on top minus straight k with hat on top right parenthesis space plus straight lambda left parenthesis 7 straight i with hat on top space minus 5 straight j with hat on top plus straight k with hat on top right parenthesis

    Question 264
    CBSEENMA12035768

    Prove that if E and F are independent events, then the events E and F' are also independent.

    Solution

    Two events E and F are independent if
    P(E ∩ F) = P(E).P(F)
    Now,
    P(E ∩ F') = P(E) – P(E ∩ F)
    = P(E) – P(E). P(F)
    = P(E)[1 – P(F)]
    = P(E).P(F')
    E and F' are independent events.
    P(E ∩ F) = P(E).P(F)
    Hence prove

    Question 265
    CBSEENMA12035770

    Find space integral fraction numerator dx over denominator straight x squared space plus 4 straight x space plus 8 end fraction

    Solution
    integral fraction numerator 1 over denominator straight x squared space plus 4 straight x space 8 end fraction dx
straight I space equals space integral fraction numerator 1 over denominator straight x squared plus 4 straight x space plus 8 end fraction dx
equals space integral fraction numerator 1 over denominator left parenthesis straight x plus 2 right parenthesis squared space plus 2 squared end fraction dx
By space using space Integral space Formula
integral fraction numerator 1 over denominator straight x squared space plus straight a squared end fraction space dx space equals space 1 over straight a tan to the power of negative 1 end exponent open parentheses straight x over straight a close parentheses
equals 1 half tan to the power of negative 1 end exponent open parentheses fraction numerator straight x plus 2 over denominator 2 end fraction close parentheses space plus straight C
    Question 266
    CBSEENMA12035776

    Find integral fraction numerator 2 straight x over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x squared plus 2 right parenthesis squared end fraction dx

    Solution
    Let space straight x squared space equals space straight y
rightwards double arrow space 2 xdx space equals space dy
rightwards double arrow space dx space equals space fraction numerator dy over denominator 2 straight x end fraction
integral fraction numerator dy over denominator left parenthesis straight y plus 1 right parenthesis left parenthesis straight y plus 2 right parenthesis squared end fraction
Let space fraction numerator 1 over denominator left parenthesis straight y plus 1 right parenthesis left parenthesis straight y plus 2 right parenthesis squared end fraction space equals space fraction numerator straight X over denominator straight y plus 1 end fraction space plus fraction numerator straight Y over denominator straight y plus 2 end fraction space plus fraction numerator straight Z over denominator left parenthesis straight y plus 2 right parenthesis squared end fraction...... space left parenthesis 1 right parenthesis

    ⇒ 1 = X (y+2)2 + Y(y+1)(y+2)+C(y+1).....(2)
    Putting y = -2 in (2)
    1 = Z(-2+1)
    ⇒Z = -1
    Putting y = -1 in (2)
    1 = X(-1 +22)
    ⇒1 = A (1)
    ⇒A =1
    Putting y =0 in (2)
    1 = 4X + Y(2) +Z
    ⇒ 1=4 + 2Y-1
    ⇒ 1 =3 +2Y
    ⇒ -2 = 2Y
    ⇒ Y = -1
    fraction numerator 1 over denominator left parenthesis straight y plus 1 right parenthesis left parenthesis straight y plus 2 right parenthesis squared end fraction space equals space fraction numerator 1 over denominator straight y plus 1 end fraction minus fraction numerator 1 over denominator straight y plus 2 end fraction minus fraction numerator 1 over denominator left parenthesis straight y plus 2 right parenthesis squared end fraction
rightwards double arrow space integral fraction numerator dy over denominator left parenthesis straight y plus 1 right parenthesis left parenthesis straight y plus 2 right parenthesis squared end fraction space equals space integral fraction numerator begin display style dy end style over denominator straight y plus 1 end fraction minus integral fraction numerator dy over denominator straight y plus 2 end fraction minus integral fraction numerator dy over denominator left parenthesis straight y plus 2 right parenthesis squared end fraction
equals log space vertical line straight y plus 1 vertical line minus log space vertical line straight y plus 2 vertical line space plus fraction numerator 1 over denominator straight y plus 2 end fraction space plus straight C
Hence comma space integral fraction numerator 2 straight x over denominator left parenthesis straight x squared plus 1 right parenthesis left parenthesis straight x squared plus 2 right parenthesis squared end fraction dx space equals space log space vertical line straight x squared plus 2 vertical line space plus fraction numerator 1 over denominator straight x squared plus 2 end fraction plus straight C

    Question 267
    CBSEENMA12035777

    Evaluate: integral subscript 0 superscript straight pi fraction numerator straight x space sin space straight x over denominator 1 plus cos squared x end fraction dx

    Solution

     integral subscript 0 superscript straight pi fraction numerator straight x space sin space straight x over denominator 1 plus cos squared x end fraction dx space space space...... space left parenthesis straight i right parenthesis
open square brackets By space using space integral subscript 0 superscript straight a space straight f left parenthesis straight x right parenthesis dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis dx close square brackets
we space get
space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space sin space left parenthesis straight pi minus straight x right parenthesis over denominator 1 plus cos squared space left parenthesis straight pi minus straight x right parenthesis end fraction dx space

space equals space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space sin space straight x over denominator 1 plus cos squared space straight x end fraction dx space space....... space left parenthesis ii right parenthesis
    Adding (i) and (ii) we get
    2 straight I space equals space integral subscript 0 superscript straight pi space fraction numerator straight x space sin space straight x over denominator 1 space plus space cos squared straight x end fraction space dx space plus space integral subscript 0 superscript straight pi fraction numerator left parenthesis straight pi minus straight x right parenthesis space sin space straight x over denominator 1 plus space cos squared space straight x end fraction dx
space equals space integral subscript 0 superscript straight pi space fraction numerator left parenthesis straight x space plus straight pi space minus straight x right parenthesis space Sin space straight x over denominator 1 plus space cos squared straight x end fraction space dx
2 straight I space equals space integral subscript 0 superscript straight pi fraction numerator straight pi space sin space straight x over denominator 1 space space plus space cos squared straight x end fraction space dx
straight I space equals space integral subscript 0 superscript straight pi straight pi over 2 fraction numerator space sin space straight x over denominator 1 plus cos squared space straight x space end fraction dx

    Let cos x = t,

    -sin xdx = dt
    also, x = 0, t = cos 0 = 1 and x = π, t= cos π=-1
    straight I space equals space straight pi over 2 space integral subscript 1 superscript negative 1 end superscript space fraction numerator negative 1 over denominator 1 plus straight t squared end fraction dt
straight I space equals space minus straight pi over 2 open square brackets tan to the power of negative 1 end exponent space straight t close square brackets subscript 1 superscript negative 1 end superscript
space equals space minus straight pi over 2 open square brackets tan to the power of negative 1 end exponent space left parenthesis negative 1 right parenthesis minus tan to the power of negative 1 end exponent space left parenthesis 1 right parenthesis close square brackets
space equals space minus straight pi over 2 open square brackets negative straight pi over 4 minus straight pi over 4 close square brackets space equals straight pi over 2 space straight x space fraction numerator 2 straight pi over denominator 4 end fraction
straight I space equals space straight pi squared over 4

    Question 268
    CBSEENMA12035778

    Evaluate:integral subscript 0 superscript 3 divided by 2 end superscript vertical line space straight x space sin space πx vertical line space dx

    Solution

    integral subscript 0 superscript 3 divided by 2 end superscript vertical line space straight x space sin space πx vertical line space dx
    For 0 < x < 1, x sinπx dx
    For 1 < x <3/2, x sinπx< 0
    Applying these in equation
    integral subscript 0 superscript 3 divided by 2 end superscript vertical line straight x space sin space πx vertical line space dx space equals space integral subscript 0 superscript 1 space straight x space sin space πdx space minus space integral subscript 1 superscript 3 divided by 2 end superscript straight x space sin space straight pi space straight x space dx
Let space straight I space equals space integral straight x space sin space straight pi space straight x space dx
space equals space straight x integral sinπ space straight x space dx space minus space integral open parentheses straight d over dx straight x integral sin space straight pi space straight x space dx close parentheses dx
space equals space straight x open parentheses negative fraction numerator cos space πx over denominator straight pi end fraction close parentheses minus integral open parentheses fraction numerator negative cos space straight pi space straight x over denominator straight pi end fraction close parentheses space dx
space equals space fraction numerator negative straight x space cos space straight pi space straight x over denominator straight pi end fraction space plus space fraction numerator sin space straight pi space straight x over denominator straight pi squared end fraction

    Now applying the limits we get,
    integral subscript 0 superscript 3 divided by 2 end superscript vertical line space straight x space sin space straight pi space straight x vertical line space dx space
equals space open square brackets fraction numerator negative straight x space cos space straight pi space straight x over denominator straight pi end fraction space plus fraction numerator sin space straight pi space straight x over denominator straight pi squared end fraction close square brackets subscript 0 superscript 1 space minus space open square brackets fraction numerator negative straight x space cos space straight pi space straight x over denominator straight pi end fraction space plus fraction numerator sin space straight pi space straight x over denominator straight pi squared end fraction close square brackets subscript 1 superscript 3 divided by 2 end superscript
open square brackets open parentheses fraction numerator negative cos space straight pi over denominator straight pi end fraction plus fraction numerator sin space straight pi over denominator straight pi squared end fraction close parentheses minus left parenthesis 0 plus 0 right parenthesis close square brackets minus open square brackets open parentheses fraction numerator negative begin display style 3 over 2 end style space cos begin display style fraction numerator 3 straight pi over denominator 2 end fraction end style over denominator straight pi end fraction space plus fraction numerator sin begin display style fraction numerator 3 straight pi over denominator 2 end fraction end style over denominator straight pi squared end fraction close parentheses space minus space open parentheses fraction numerator negative cos space straight pi over denominator straight pi end fraction plus fraction numerator sin space straight pi over denominator straight pi squared end fraction close parentheses close square brackets
open square brackets open parentheses 1 over straight pi plus 0 close parentheses close square brackets minus open square brackets open parentheses 0 minus 1 over straight pi squared close parentheses minus open parentheses 1 over straight pi plus 0 close parentheses close square brackets
space equals space 1 over straight pi space plus 1 over straight pi squared space plus 1 over straight pi
space equals space 2 over straight pi space plus space 1 over straight pi squared
space equals space fraction numerator 2 straight pi space plus 1 over denominator straight pi squared end fraction

    Question 269
    CBSEENMA12035782

    The random variable X can take only the values 0, 1, 2, 3. Given that P(X =0) = P(X = 1) = p and P(X = 2) = P(X = 3) such that Σpixi2 = 2Σpixi, find the value of p.

    Solution

    It is given that the random variable X can take only the values 0,1,2,3.
    Given:
    P(X = 0) = P( X =1) =p
    P(X =2) =P(X =3)
    Let P (X =2) = P(X =3) =q
    Now,
    P(X =0) + P(X =1) +P(X =2) +P(X =3) =1
    ⇒ p +p+(q+q) = 1
    since Σpixi2 = 2Σpixi,
     rightwards double arrow space 0 space plus straight p left parenthesis 1 right parenthesis squared space plus open parentheses fraction numerator 1 minus 2 straight p over denominator 2 end fraction close parentheses open parentheses left parenthesis 2 squared plus 3 squared close parentheses space equals space 2 open square brackets 0 space plus straight p space plus open parentheses fraction numerator 1 minus 2 straight p over denominator 2 end fraction close parentheses left parenthesis 2 plus 3 right parenthesis close square brackets
rightwards double arrow space straight p space plus 13 over 2 left parenthesis 1 minus 2 straight p right parenthesis space equals 2 space open square brackets straight p space plus 5 over 2 left parenthesis 1 minus 2 straight p right parenthesis close square brackets
rightwards double arrow space straight p space plus 13 over 2 minus 12 straight p space equals space minus 8 straight p plus 5
rightwards double arrow space 4 straight p space equals space 3 over 2
rightwards double arrow space straight p space equals space 3 over 8

    Question 270
    CBSEENMA12035783

    Often it is taken that a truthful person commands, more respect in the society. A man is known to speak the truth 4 out of 5 times. He throws a die and reports that it is a six.
    Find the probability that it is actually a six.
    Do you also agree that the value of truthfulness leads to more respect in the society?

    Solution

    Let H1 be the event that 6 appears on throwing a die
    H2 be the event that 6 does not appear on throwing a die
    E be the event that he reports it is six
    straight P left parenthesis straight H subscript 1 right parenthesis space equals space 1 over 6 comma space straight P left parenthesis straight H subscript 2 right parenthesis space equals space 1 minus 1 over 6 space equals space 5 over 6
straight P left parenthesis straight E divided by straight H subscript 1 right parenthesis space equals space 4 over 5 comma space straight P left parenthesis straight E divided by straight H subscript 2 right parenthesis space equals space 1 fifth
straight P left parenthesis straight H subscript 1 divided by straight E right parenthesis space equals space fraction numerator straight P left parenthesis straight H subscript 1 right parenthesis. straight P left parenthesis straight E divided by straight H subscript 1 right parenthesis over denominator straight P left parenthesis straight H subscript 1 right parenthesis. straight P left parenthesis straight E divided by straight H subscript 1 right parenthesis space plus straight P left parenthesis straight H subscript 2 right parenthesis straight P left parenthesis straight E divided by straight H subscript 2 right parenthesis end fraction
space equals space 4 over 9
    Yes ruthless leads to more respect in the society.

    Question 271
    CBSEENMA12035789

    Find the area bounded by the circle x2 + y2 = 16 and the line √3y=x in the first quadrant, using integration.

    Solution

    The area of the region bounded by the circle, x2+y2=16, x=√3y, and the x-axis is the area OAB.

    Solving x2+y2=16 and x=√3y, we have

    (√3y)2+y2=16
    ⇒3y2+y2=16
    ⇒4y2=16
    ⇒y2=4
    ⇒y=2
    (In the first quadrant, y is positive)

    When y = 2, x = 2√3

    So, the point of intersection of the given line and circle in the first quadrant is (2√3,2).

    The graph of the given line and circle is shown below:

    Required area = Area of the shaded region = Area OABO = Area OCAO + Area ACB
    Area OCAO = 12×2√3×2=2√3 sq units
    Area space ABC space equals space integral subscript 2 square root of 3 end subscript superscript 4 space straight y space dx
space equals space integral subscript 2 square root of 3 end subscript superscript 4 square root of 16 minus straight x squared dx end root
space equals space open square brackets straight x over 2 square root of 16 minus straight x squared end root space plus 16 over 2 space sin to the power of negative 1 end exponent space straight x over 4 close square brackets subscript 2 square root of 3 end subscript superscript 4
space equals space open square brackets open parentheses 0 plus space 8 space sin to the power of negative 1 end exponent 1 close parentheses minus open parentheses fraction numerator 2 square root of 3 over denominator 2 end fraction space straight x space 2 space plus 8 space straight x space sin to the power of negative 1 end exponent fraction numerator square root of 3 over denominator 2 end fraction close parentheses close square brackets
space equals space 8 space straight x space straight pi over 2 minus 2 square root of 3 space minus 8 space straight x space straight pi over 3
space equals open parentheses fraction numerator 4 straight pi over denominator 3 end fraction minus 2 square root of 3 space close parentheses space sq space unit
therefore space Required space area space equals space open parentheses fraction numerator 4 straight pi over denominator 3 end fraction minus 2 square root of 3 close parentheses space plus 2 square root of 3 space equals space fraction numerator 4 straight pi over denominator 3 end fraction space sq space units

    Question 272
    CBSEENMA12035803

    Evaluate: cos 2x + 2 sin2 x cos2 x  dx

    Solution

    I = cos 2 x  + 2 sin2 x cos2 x dxI = 1-2 sin2 x  + 2 sin 2xcos2 x I = sec2 x dxI = tan x + C

    Question 273
    CBSEENMA12035812

    Find:2 cos x(1-sin x) (1 + sin 2 x) dx

    Solution

    Let I = 2 cos x(1-sin x) (1 + sin2 x) dxLet sin x = tcos dx = dt I = 2(1 -t)(1 + t2)dtconsider2(1-t)(1 +t2) = A1- t + Bt + Ct2 + 1 = A (t2 + 1)  + (Bt +C)(1- t)(1- t)(t2 +1) 2 At2 + A + Bt + C - Bt2 - Ct = (A-B)t2 + (B-C)t + (A+ C)A -B = 0, B- C = 0  A +C = 2A = 1, B =1, C = 1 I = 11-t + 2t2(t2 +1) + 1t2 + 1dt= - log |1 - t| +  12 log |t2 + 1| + tan-1 (t) + C = 12log t2 + 1(1 -t)2 + tan-1 (t) + C = 12 log sin2 x  + 1(1 - sin x)2 + tan-1 (sin x) + C

    Question 274
    CBSEENMA12035818

    Evaluate: sin x + cos x16 + 9 sin 2x dx

    Solution

    Let I = sin x  + cos x16 + 9 2x dx

    Here, we express the denominator in terms of sin x - cos x which is the integration of numerator.

    Clearly,

    (sin x  - cos x)2 = sin2 x + cos2 x - 2 sin xcos x = 1-sin 2x sin 2 x  = 1 - (sin x - cos x)2 I = 0π/4sin x  + cos x16 + 9 1 - (sin x - cos x)2 dx I = 0π/4sin x + cos x25-9 (sin x - cos x)2 dxLet sin x - cosx = t,Then , d (sin x - cos x) = dt (cos x + sin x ) dx = dtalso, x = 0 t = sin 0 - cos 0  = - 1and  x = π4t = sin π4 - cos π4 = 0 I= -10 dt25-9t2 = 19-10 dt259-t2 =19 -10dt532-t2 I = I9 x 12 (5/3) log 53 + t5/3 - t-10 I=130log - 1 log 2/38/3  = 130 log 1 - log 14 = 130 [ log 1 + log 4 ]  = 130 log 4  = 115 log 2 

    Question 275
    CBSEENMA12035820

    Evaluate:13(x2 + 3x + ex) dx

    Solution

    I = 13(x2 + 3x+ ex) dx = ab f(x) dxwhen f(x) = x2 + 3x + ex; a =1, b =3h =b-an = 3-1n =2nf (a +rh) = f( 1 +rh) = (1 +rh)2 + 3(1 +rh) +e1+rh = 4 + 5rh +r2h2 +e x erh = r2h2 + 5rh + 4 +e x erh

    ab f(x) dx = limn  r =1n hf(a +rh)limn r = 1nh (r2h2 + 5rh + 4 + ex erh)limn 2r = 1nr2h2 +r = 1nrh2  + r = 1n4h +er = 1nerh x hlimn8n3 x n (n +1)(2n +1)6 x 5 x 4n2xn(n+1)2 + 4 x 2n x n + ehenh-1eh-1.h

     

    abf(x) dx = 43 x 1 x limn 1 + 1n x limn 2 + 1n+limn 10 x 1 x 1 + 1n + 8 + limh0eh+1(e2-1)eh-1h = 43 x 1 x 2 + 10 x 1 x 1  + 8 + e(e2 - 1)1 = 83 + 10 + 8 + e3-e = 83 + 18 + e3-e = 623 + e3 -e

    Question 276
    CBSEENMA12035832

    Evaluate: x21 + x3dx

    Solution

    x21 + x3dxLet   1 + x3 = t 0 + 3x2 dx = dt x2 dx = dt3x21 + x3 dx = dt3t                                = 13dtt                                = 13log t + c                                =  13log  1 + x3  + c

    Question 277
    CBSEENMA12035833

    Evaluate: 04dx1 + x2 dx

    Solution

    04dx1 + x2 dxLet  X = tanθ  θ = tan-1Xdx = sec2θ When  X = 0,   θ = tan-1(0) = 0When  X = 1,  θ = tan-11 = π4 04dx1 + x2 =  0π4sec2θ1 + tan2θ                           = 0π4sec2θsec2θ                              =   0π4                            = θ0π4                        =  π4 - 0                        =  π4                                

    Question 278
    CBSEENMA12035844

    Evaluate: 0πxsinx1 + cos2x dx

    Solution

    I = 0πxsinx1 + cos2xdx           .............(1)I = 0π(π - x) sin (π - x)1 + cos2 (π - x)dxI = 0π(π - x) sin x1 + cos2 xdxI = 0ππ  sin x1 + cos2 xdx -  0πxsinx1 + cos2xdx           ..........(2)

    Adding (1) and (2), we get:

     

    2I = 0ππ sinx1 + cos2x dxNow, let  cosx = t  -sinx dx = dtWhen   x = π,  t = cosπ = -1When    x = 0,  t = cos0 = 12I =  1-1π - dt1 + t2 2I = π  1-1 11 + t2 dt2I = π  tan-1t 1-12I = π  tan-1 1 - tan-1 -1  2I = π π4 - -π42I = π22 I = π24

    Question 279
    CBSEENMA12035857

    Evaluate: -aa a - xa + x dx

    Solution

    I = -aa a - xa + x  dx  =  -aa a - xa2 - x2 dx  =   -aa aa2 - x2 dx -   -aa  xa2 - x2 dx  =  I1  + I2Where I1 =-aa aa2 - x2 dx, which is the integral of an even functionAnd    I2 =-aa xa2 - x2 dx, which is the integral of an even function,and so   I2 =0

    Now,

    I = I1 = -aa aa2 - x2 dx  = 20a aa2 - x2 dx =  2a0a 1a2 - x2 dx = 2a. sin-1 xa0a =  2a.sin-1 1 - sin-1 0 =  2aπ2 = πa

    Question 280
    CBSEENMA12035863

    Evaluate: sec2  7 - x  dx

    Solution

    I = sec2  7 - x  dxSubstituting  7 - x =t  -dx = dt I = -sec2 t.dt       = - tan  7 - x = C

    Question 281
    CBSEENMA12035864

    If 01 3x2 + 2x + k  dx = 0  , find the value of k.

    Solution

     Given: 01 3x2 + 2x + k dx = 0 3x33 + 2x22 + kx 01 = 0 x3 +x2 + kx 01 = 0  1+ 1 + k = 0 k = -2

    Question 282
    CBSEENMA12035873

    Evaluate:  ex5 - 4 ex - e2x dx

    Solution

    I =  ex5 - 4ex - e2x dxLet  ex = t     exdx = dt

    Now integral I becomes,

         I = dt5 - 4t - t2 I = dt5 + 4 - 4 - 4t - t2 I = dt9 -(4 + 4t + t2 ) I = dt9 -(t + 2 )2 I = dt32 -(t + 2 )2 I = sin-1 (t + 2 )3 +C I = sin-1 ( ex+ 2 )3 +C

    Question 283
    CBSEENMA12035874

    Evaluate: x - 4 ex x - 2 3 dx.

    Solution

    I =x - 4 ex x - 2 3 dxI = exx - 2 x - 2 3 - 2 x - 2 3 dxI = ex1 x - 2 2 - 2 x - 2 3 dx

    Thus the  given integral is of the form,

    I =  ex  f ( x ) +f' ( x )  dx   where,  f ( x ) = 1 x - 2 2;  f' ( x ) = -2 x - 2 3I =  ex x - 2 2 dx  -  2ex x - 2 3 dx    = ex x - 2 2 -  ex ( - 2 ) x - 2 3 dx  -  2ex x - 2 3 dx  + CSo,   I = ex x - 2 2  + C

    Question 284
    CBSEENMA12035890

    Evaluate: 0π ecosxecosx + e-cosx

    Solution

    Let   I = 0π ecosxecosx + e-cosx dx Using  0af ( x ) = 0af ( a - x ) dx  I = 0π ecos  π - x ecos  π - x   + e-cos  π - x  . dx2I = 0π e- cos x + e cos xecos x  + e-cos x . dxI = 12 0π dx = 12  π - 0    I = π2

    Question 285
    CBSEENMA12035891

    Evaluate: 0π2  2 log sin x - log sin 2x  dx

    Solution

    I = 0π2  2 log sin x - log sin 2x  dxI = 0π2  log sin2 x 2 sin x . cos x . dx I = 0π2 log  tan x 2 . dx                .............(i)Using property    0af ( x ) dx = 0af ( a - x ) dx

     

    We get,

     

    I = 0π2 log  tan π2 - x 2 dx I = 0π2 log cot x2 dx                    ........(ii)

     

    Adding (i) and (ii)

     

    2I = 0π2   log tan x2 + log cot x2  dx 2I = 0π2 log tan x2  cot x2  dx I = 120π2 log 14 dx I = 12 log 14  x π2  I = 12 log 142  x π2  I =  log 12  x π2  I = π2  log 12

    Question 286
    CBSEENMA12035897

    Evaluate: log xx dx

    Solution

    I =  log xx dx

    Substituting  log x = t

    Differentiating w.r.t. x, we get

    1x dx = dt

    On substitution, we get

    I =  log xx dx=  t. dt = t22 + C =  log x 22 + C

    Question 287
    CBSEENMA12035916

    Evaluate: 0π x1 + sinx  dx

    Solution

    Let I = 0π x1 + sinx dx          .........(i)Using the property  0a f ( x ) dx =  0a f ( a -x ) dx I =  0π π - x1 + sin  π - x  dx       = 0π π - x1 + sin x dx           .........(ii)

    Now adding (i) and (ii), we get

    2I = 0π x1 + sinx dx + 0π π - x1 + sinx dx    = 0π π1 + sinx dx    = π 0π 11 + sinx dx    =  π 0π  1 - sinx  1 - sin2x  dx    =  π 0π  1 - sinx  cos2x  dx    = π   0π 1cos2x - sinxcos2x  dx 

        = π  0π sec2 x - secx tanx dx    = π 0π sec2 x dx - 0π secx tanx dx     = π   tanx 0π  -  secx 0π  2I =  π  2    I =  πSo, 0π x1 + sinx dx = π

    Question 288
    CBSEENMA12035917

    Evaluate:  ex  sin4x - 41 - cos4x dx

    Solution

    Let I =  ex sin4x - 41 - cos4x dx        = ex sin2(2x) - 41 - cos2(2x) dx        =  ex 2 sin2x cos2x- 42sin2(2x) dx     [ Using, sin2x = 2sinx.cosx and 2sin2x = 1 - cos ( 2x ) ]        =   ex 2 ( sin (2x ) cos ( 2x ) - 2 )2sin2(2x) dx         =   ex   sin (2x ) cos ( 2x )sin2(2x) - 2sin2(2x) dx         =   ex   cot (2x ) -2cosec2(2x)  dxNow, let   f ( x ) = cot ( 2x )    then     f ( x ) = -2cosec2 ( 2x )I =   ex  f ( x ) +  f' ( x )  dx

    So, I = ex f ( x ) + C         =  ex cot ( 2x ) + C,     Where C is a constanttherefore,   ex  sin4x - 41 - cos4x  dx = ex cot ( 2x ) + C 

    Question 289
    CBSEENMA12035918

    Evaluate:  1 - x2x  1 - 2x  dx

    Solution

    1 - x2x  1 - 2x  dxHere 1 - x2x  1 - 2x  is an improper rational  fraction.

    Reducing it to proper rational fraction gives

    1 - x2x  1 - 2x  = 12 + 12  2 - xx  1 - 2x        .......(i)Now, let 2 - xx  1 - 2x  = Ax + B  1 - 2x  2 - xx  1 - 2x  = A   1 - 2x  + Bxx   1 - 2x  2 - x = A - x 2A - B 

    Equating the coefficients we get,  A = 2  and  B = 3

    So, 2 - xx  1 - 2x  = 2x + 3 1 - 2x 

    Substituting in equation  (i), we get

    1 - x2x  1 - 2x  = 12 + 12  2x + 3  1 - 2x i.e.  1 - x2x  1 - 2x  dx  =   12 + 12  2x + 3  1 - 2x   dx                                      =  dx2 + dxx + 32  dx  1 - 2x                                        = x2 + log  x  + 32 x 1 - 2  log  1 - 2x  + C                                    = x2 + log  x  - 34 x  log  1 - 2x  + C.

    Question 290
    CBSEENMA12035923

    Evaluate 13  3 x2 + 2 x  dx  as limit of sums.

    Solution

    I = 13  3 x2 + 2x  dx

    Here    a = 1,   b = 3

    f ( x ) = 3 x2 + 2x         h = b - an = 2nSince,  ab f ( x ) dx = limh  0 h  f ( a ) + F ( a + h ) ......+ f ( + ( n - 1 ) h )so, 13  3 x2 + 2x  =  limh  0 h [ ( 3 ( 1 )2 + 2 ( 1 ) ) + ( 3  ( 1 +h )2  + 2 ( 1  +h ) ) +                                   3 ( 1 + 2h )2 + 2 ( 1 + 2h ) )..........+ 3 ( 1 + ( n - 1 ) h )2 + 2 ( 1 + ( n - 1 ) h ) ]                                 = limh  0 h [ 3 ( n ) + 3 ( h2 + 4 h2 + .........+ ( n - 1 )2 h2 ) + 3 ( 2h + 4h + .......+                                     2 ( n - 1  ) h ) + 2 n + 2 ( h + 2 h + ..........+ ( n - 1 ) h ) ]                                 =  limh  0 h [ 5 n h + 3 h3 ( 12 + 22 + .....+ ( n - 1 )2 + 6 h2 ( 1 + 2 + ...........+ ( n - 1 ) )+                                          2 h2 ( 1 + 2 + ( n - 1 ) ) ]

                                   = limh  0  5 n h + 3h3 × ( n - 1 ) n ( 2n - 1 )6 + 8 h2 ( n ) ( n - 1 )2                     = limh  0  10 +  n h - h  n h  2 n h - h 2 + 4 ( n h ) ( n h - h )                     =  10 + 2 ×2 × 42 + 4 x 2 x 2                     = 10 + 8 + 16 = 34

    Question 291
    CBSEENMA12035937

    Write the value of  sec x  sec x + tan x  dx

    Solution

     sec x  sec x + tan x  dx ( sec2 x +  sec x  tan x )  dx ( sec2 x  dx  +  sec x  tan x dx= tan x  + sec x + C,  where C is a constant.

    Question 292
    CBSEENMA12035938

    Write the value of  dxx2 + 16

    Solution

     dxx2 + 16=  dx( x )2 + ( 4 )2= 14 tan-1  x4  + C,   where C is a constant.

    Question 293
    CBSEENMA12035951

    Evaluate:  5 x + 3 x2 + 4 x + 10 dx

    Solution

     5 x + 3 x2 + 4 x + 10 dxNow,  5 x + 3 = A ddx x2 + 4 x + 10  + B  5 x + 3 = A  2 x + 4  + B  5 x + 3 = 2 A x + 4 A  + B 2 A = 5    and   4 A + B = 3 A = 52Thus, 4  52  + B = 3 10 + B = 3 B = 3 - 10 = -7

    On substituting the values of  A  and  B,  we get

      5 x + 3  x2 + 4 x + 10 dx =  52 ddx x2 + 4 x + 10  - 7  x2 + 4 x + 10 dx                                        =  52  2 x +4  - 7  x2 + 4 x + 10  dx                                        = 52  2 x +4 x2 + 4 x + 10 dx - 7 dx x2 + 4 x + 10                                        = 52 I1 - 7 I2          ...........( i )

    I2 =  2 x + 4 x2 + 4 x + 10 dxPut   x2 + 4 x + 10 = z22 x + 4  dx = 2 z dzThus,   I1 =  2 zz dz  = 2 z = 2  x2 + 4 x + 10 + C1I2 =  dx x2 + 4 x + 10     =  dx x2 + 4 x + 4 + 6    =  dx ( x + 2 )2 +   6 2    = log  ( x + 2 ) +  x2 + 4 x + 10   + C2

    Substituting  I1  and  I2  in  ( i ),  we get

      5 x + 3 x2 + 4 x + 10 = 52  2  x2 + 4 x + 10  + C1  - 7  log   x + 2  +  x2 + 4 x + 10  + C2 =  5  x2 + 4 x + 10 - 7  log   x + 2  +  x2 + 4 x + 10   + 52 C1 - 7 C2=  5  x2 + 4 x + 10 - 7  log   x + 2  +  x2 + 4 x + 10   +C,   where  C = 52 C1 - 7 C2

    Question 294
    CBSEENMA12035952

    Evaluate:  2x  x2 + 1   x2 + 3  dx

    Solution

    I =  2 x x2 + 1   x2 + 3  dxLet  x2 = z 2 x dx = dz I =  dz z + 1   z + 3 

    By partial fraction,

    1 z + 1   z + 3  = A z + 1  + B z + 3  1 = A  z + 3  + B  z + 1 Putting  z = - 3,   we obtain:1 = - 2 BB = - 12 A = 12 1 z + 1   z + 3  = 12 z + 1  +  - 12 z + 3  dz z + 1   z + 3  = 12  dz z + 1   -  12  dz z + 3                                          = 12 log  z + 1  - 12 log  z + 3   + C   2 x dx x2 + 1   x2 + 3  =  12 log   x2 + 1  - 12 log   x2 + 3   + C

    Question 295
    CBSEENMA12035962

    Evaluate: 0π2 2 sin x cos x tan-1  sin x  dx

    Solution

    Consider the given integral

    I = 0π2 2 sin x cos x tan-1  sin x  dxLet  t = sin x dt = cos x dxWhen   x = π2,    t = 1When    x= 0,       t = 0Now,    2 sin x cos x tan-1  sin x  dx=  2 t  tan-1 t  dt

    =  tan-1 t   2 t dt  -   ddt .  tan-1   2 t dt   dt=  tan-1 t    2 . t22  -   11 + t2 x 2. t22  dt= t2  tan-1 t  -  t21 + t2 dt=  t2  tan-1 t  -   1 - 11 + t2  dt=   t2  tan-1 t  - t + tan-1 t

     I = 0π2 2 sin x cos x tan-1  sin x  dx=  t2 tan-1 t  -  t +  tan-1 t 01=  12  tan-1 1  -  1 +  tan-1 1  -   02  tan-1 0  -  0 +  tan-1 0 =  1  x π4 - 1 + π4  - 0= π4 - 1 + π4= π2 - 1

    Question 296
    CBSEENMA12035963

    Evaluate: 0π2 x sin x cos xsin4 x + cos4 x dx

    Solution

    I = 0π2 x sin x cos xsin4 x + cos4 x dx                            ............( i )Using the property  0a f ( x ) dx = 0a f ( a- x ) dxI = 0π2 π2 - x   sin π2 - x   cos π2 - x sin4 π2 - x  + cos4 π2 - x  dx I = 0π2 π2 - x  cos x sin x sin4 x + cos4 x dx            .............( ii )

    Adding  ( i )  and  ( ii ),

    2 I = 0π2  π2 . sin x cos x sin4 x + cos4 x   dx I = π4  0π2   sin x cos x sin4 x + cos4 x    dx= π4  0π2    sin x cos xcos4 x sin4 x cos4 x + 1   dx=  π4  0π2  tan x sec2 xtan4 x + 1 dx

    Put  tan2 x = z

     2 tan x sec2 x  dx =  dz

     tan x sec2 x dx = dz2When  x = 0,   z = 0   and   when  x = π2,   z =  I = π4 0 dz2z2 + 1  I = π8 0 dz1+ z2           = π8  tan-1  z  0          = π8  tan-1  -  tan-1 0          = π8  π2 - 0           = π216

    Question 297
    CBSEENMA12036014

    The integral integral fraction numerator 2 straight x to the power of 12 space plus space 5 straight x to the power of 9 over denominator left parenthesis straight x to the power of 5 space plus space straight x cubed space plus space 1 right parenthesis cubed end fraction space dx is equal to 

    • fraction numerator negative straight x to the power of 5 over denominator left parenthesis straight x to the power of 5 space plus straight x cubed plus 1 right parenthesis squared end fraction space plus straight C
    • fraction numerator straight x to the power of 10 over denominator 2 left parenthesis straight x to the power of 5 space plus straight x cubed plus 1 right parenthesis squared end fraction space plus straight C
    • fraction numerator straight x to the power of 5 over denominator 2 left parenthesis straight x to the power of 5 space plus straight x cubed plus 1 right parenthesis squared end fraction space plus straight C
    • fraction numerator negative straight x to the power of 10 over denominator left parenthesis straight x to the power of 5 space plus straight x cubed plus 1 right parenthesis squared end fraction space plus straight C

    Solution

    B.

    fraction numerator straight x to the power of 10 over denominator 2 left parenthesis straight x to the power of 5 space plus straight x cubed plus 1 right parenthesis squared end fraction space plus straight C Let space straight I space space equals space integral fraction numerator 2 straight x to the power of 12 space plus 5 straight x to the power of 9 over denominator left parenthesis straight x to the power of 5 space plus straight x cubed space plus 1 right parenthesis end fraction dx
space equals space integral fraction numerator 2 straight x to the power of 12 space plus space 5 straight x to the power of 9 over denominator straight x to the power of 15 left parenthesis 1 space plus space straight x to the power of negative 2 end exponent space plus straight x to the power of negative 5 end exponent right parenthesis cubed end fraction space dx
space equals space integral space fraction numerator 2 straight x to the power of negative 3 end exponent space plus 5 straight x to the power of negative 6 end exponent over denominator left parenthesis 1 plus straight x to the power of negative 2 end exponent plus straight x to the power of negative 5 end exponent right parenthesis cubed end fraction dx
Now comma space put space 1 plus space straight x to the power of negative 2 end exponent space plus straight x to the power of negative 5 end exponent space equals space straight t
rightwards double arrow space left parenthesis negative 2 straight x to the power of negative 3 end exponent space minus 5 straight x to the power of negative 6 end exponent right parenthesis space dx space equals space dt
rightwards double arrow space left parenthesis 2 straight x to the power of negative 3 end exponent space plus space 5 straight x to the power of negative 6 end exponent right parenthesis space dx space equals space minus dt
therefore comma
straight I space equals space minus integral dt over straight t cubed space equals space minus integral straight t to the power of negative 3 end exponent space dt
equals negative space fraction numerator straight t to the power of negative 3 space plus space 1 end exponent over denominator negative 3 plus 1 end fraction plus space straight C space equals fraction numerator space 1 over denominator 2 straight t end fraction space plus space straight C
equals space fraction numerator straight x to the power of 10 over denominator 2 left parenthesis straight x to the power of 5 space plus straight x cubed space plus 1 squared right parenthesis end fraction space plus straight C
    Question 298
    CBSEENMA12036018

    Two sides of a rhombus are along the lines, x−y+1=0 and 7x−y−5=0. If its diagonals intersect at (−1, −2), then which one of the following is a vertex of this rhombus?

    • (−3, −9)

    • (−3, −8)

    • (1/3, -8/3)

    • (-10/3, -7/3)

    Solution

    C.

    (1/3, -8/3)

    As the given lines x-y +1 =0 and 7x-y-5 = 0 are not parallel, therefore they represent the adjacent sides of the rhombus.
    On solving x-y+1 = 0  adn 7x - y -5 = 0. we get x =1 and y =2
    Thus, one of the vertex is A(1,2)

    Let the coordinate of point C be (x,y)
    Then, 
    negative 1 space equals space fraction numerator straight x plus 1 over denominator 2 end fraction
and space minus 2 space equals space fraction numerator straight y plus 2 over denominator 2 end fraction
    ⇒ x+1 =- 2 and y =-4-2
    ⇒ x=-3 and y =-6
    Hence, coordinates of C = (-3,-6)
    Note that, vertices B and D will satisfy x-y +1 =0 and 7x - y-5 = 0, therefore the coordinate of vertex D is (1/3, -8/3)

    Question 300
    CBSEENMA12036023

    The distance of the point (1, −5, 9) from the plane x−y+z=5 measured along the line x=y=z is:

    • 3 square root of 10
    • 10 square root of 3
    • fraction numerator 10 over denominator square root of 3 end fraction
    • 20 over 3

    Solution

    B.

    10 square root of 3

    the equation of the line passing through the point (1,5-9 and parallel to x =y=z is

    fraction numerator straight x minus 1 over denominator 1 end fraction space equals space fraction numerator straight y plus 5 over denominator 1 end fraction space equals space fraction numerator straight z minus 9 over denominator 1 end fraction space equals space straight lambda
    Thus, any point on this line is of the form
    (λ +1, λ-5 ,λ+9) 
    Now, if P (λ +1, λ-5, λ+9) is the point of intersection of line and plane, then
     (λ+1) - (λ-5) +λ+9 = 5
    λ +15 = 5
    λ = -10
    therefore coordinates of point P are (-9, -15,-1)
    Hence, required distance
    =equals square root of left parenthesis 1 plus 9 right parenthesis squared plus left parenthesis negative 5 plus 15 right parenthesis squared plus left parenthesis 9 plus 1 right parenthesis squared end root
equals square root of 10 squared plus space 10 squared plus 10 squared end root space equals space 10 square root of 3

    Question 301
    CBSEENMA12036024

    If the line fraction numerator straight x minus 3 over denominator 2 end fraction space equals space fraction numerator straight y plus 2 over denominator negative 1 end fraction space equals space fraction numerator straight z plus 4 over denominator 3 end fraction lies in the plane lx +my -z = 9, then l2 +m2 is equal to 

    • 26

    • 18

    • 5

    • 2

    Solution

    D.

    2

    Since the linefraction numerator straight x minus 3 over denominator 2 end fraction space equals space fraction numerator straight y plus 2 over denominator negative 1 end fraction space equals space fraction numerator straight z plus 4 over denominator 3 end fraction lies in the plane lx my-z =9, therefore we have 2l-m-3 = 0
    [∴ normal will be perpendicular to the line]
    ⇒ 2l-m = 3
    and 3l -2m +4 = 9
    [∴ point (-3,-2-4) lies on the plane
    ⇒ 3l-2m = 5
    On solving eqs (i) adn (ii), we get
    l =1 and m=-1
    therefore, l2 +m2 = 2

    Question 302
    CBSEENMA12036034

    If 12 identical balls are to be placed in 3 identical boxes, then the probability that  one of the boxes contains exactly 3 balls, is

    • 55 over 33 open parentheses 2 over 3 close parentheses to the power of 11
    • 55 space open parentheses 2 over 3 close parentheses to the power of 10
    • 220 space open parentheses 1 third close parentheses to the power of 12
    • 22 space open parentheses 1 third close parentheses to the power of 11

    Solution

    A.

    55 over 33 open parentheses 2 over 3 close parentheses to the power of 11

    There seems to be ambiguity in this question. It should be mentioned that boxes are different and one particular box has 3 balls.
    Then, number of ways = fraction numerator straight C presuperscript 12 subscript 3 space straight x space 2 to the power of 9 over denominator 3 to the power of 12 end fraction
space equals space 55 over 3 space open parentheses 2 over 3 close parentheses to the power of 11

    Question 303
    CBSEENMA12036036

    The integral integral fraction numerator dx over denominator straight x squared space left parenthesis straight x to the power of 4 plus 1 right parenthesis to the power of begin display style 3 over 4 end style end exponent end fraction space equals

    • open parentheses fraction numerator straight x to the power of 4 plus 1 over denominator straight x to the power of 4 end fraction close parentheses to the power of 1 fourth end exponent space plus straight C
    • left parenthesis straight x to the power of 4 plus 1 right parenthesis to the power of 1 fourth end exponent space plus straight C
    • negative left parenthesis straight x to the power of 4 plus 1 right parenthesis to the power of 1 fourth end exponent space plus straight C
    • negative open parentheses fraction numerator straight x to the power of 4 plus 1 over denominator straight x to the power of 4 end fraction close parentheses to the power of 1 fourth end exponent space plus straight C

    Solution

    C.

    negative left parenthesis straight x to the power of 4 plus 1 right parenthesis to the power of 1 fourth end exponent space plus straight C

    D.

    negative open parentheses fraction numerator straight x to the power of 4 plus 1 over denominator straight x to the power of 4 end fraction close parentheses to the power of 1 fourth end exponent space plus straight C integral fraction numerator dx over denominator straight x squared left parenthesis straight x to the power of 4 plus 1 right parenthesis to the power of begin display style 3 over 4 end style end exponent end fraction space equals space integral fraction numerator dx over denominator straight x to the power of 5 open parentheses 1 plus begin display style 1 over straight x to the power of 4 end style close parentheses to the power of begin display style 3 over 4 end style end exponent end fraction
Put space space 1 space plus space 1 over straight x to the power of 4 equals space straight t to the power of 4
minus 4 over straight x to the power of 5 dx space equals space 4 straight t cubed dt
rightwards double arrow space dx over straight x to the power of 5 space equals space minus space straight t cubed dt space equals space integral fraction numerator negative straight t cubed dt over denominator straight t cubed end fraction
equals space minus integral dt space equals space minus space minus straight t plus straight c space equals space minus space open parentheses 1 plus 1 fourth close parentheses to the power of 1 fourth end exponent space plus space straight C
    Question 304
    CBSEENMA12036037

    The integral integral subscript 2 superscript 4 fraction numerator log space straight x squared over denominator log space straight x squared space plus space log space left parenthesis 36 minus 12 space straight x plus straight x squared right parenthesis end fraction dx  is equal to 

    • 2

    • 4

    • 1

    • 6

    Solution

    C.

    1

    straight I space equals space integral subscript 2 superscript 4 fraction numerator log space straight x squared over denominator log space straight x squared space plus space log space left parenthesis 36 minus 12 space straight x plus straight x squared right parenthesis end fraction dx
space equals space integral subscript 2 superscript 4 fraction numerator 2 space log space straight x over denominator space 2 space log space straight x space plus space log space left parenthesis 6 minus straight x squared right parenthesis end fraction dx
space equals space integral subscript 2 superscript 4 fraction numerator 2 space log space straight x space dx over denominator 2 left square bracket log space straight x space plus space log space left parenthesis 6 minus straight x right parenthesis right square bracket end fraction dx space space space.. space left parenthesis straight i right parenthesis space
equals space integral subscript 2 superscript 4 fraction numerator log space left parenthesis 6 minus straight x right parenthesis over denominator log space left parenthesis 6 minus straight x right parenthesis space plus space log space straight x end fraction dx space space space... space left parenthesis ii right parenthesis
open square brackets because space integral subscript straight a superscript straight b straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b straight f space left parenthesis straight a plus straight b minus straight x right parenthesis dx close square brackets
On space adding space eqs. space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis comma space we space get
2 straight I space equals space integral subscript 2 superscript 4 fraction numerator log space straight x space plus space log space left parenthesis 6 minus straight x right parenthesis over denominator log space straight x space plus space log space left parenthesis 6 minus straight x right parenthesis end fraction dx
rightwards double arrow space 2 straight I space equals space integral subscript 2 superscript 4 space dx space equals space left square bracket straight x right square bracket subscript 2 superscript 4
2 straight I space equals space 2
straight I space equals space 1
    Question 305
    CBSEENMA12036040

    The number of points having both coordinates as integers that lie in the interior of the triangle with vertices (0,0), (0,41) and (41,0) is

    • 901

    • 861

    • 820

    • 780

    Solution

    D.

    780

    Required point (x,y) is such  that it satisfies
     x +y < 41
    and x> 0 and y>0
    Number of positive integral solutions of the equation x +y+ k = 41 will be number of intergral coordinates in the bounded region.

    therefore, the total number of integral coordinates,
     = straight C presuperscript 41 minus 1 end presuperscript subscript 3 minus 1 end subscript space equals space straight C presuperscript 40 subscript 2 space equals space fraction numerator 40 space factorial over denominator 2 space factorial space 38 space factorial end fraction space equals space 780

    Question 306
    CBSEENMA12036041

    Locus the image of the point (2,3) in the line (2x - 3y +4) + k (x-2y+3) = 0, k ε R is a 

    • straight line parallel to X - axis

    • a straight line parallel to Y- axis

    • circle of radius square root of 2

    • circle of radius square root of 3

    Solution

    C.

    circle of radius square root of 2

    (2x-3y +4) +k (x-2y+3) = 0  is family of lines passing through (1,2). By congruency of triangles, we can prove that mirror image (h,k) and the point (2,3) will be equidistant from (1,2).
    Therefore, Locus of (h,k) is PR = PQ
    ⇒ (h-1)2 + (k-2)2 = (2-1)2 + (3-2)2
    (x-1)2 + (y-2)2 = 2
    Locus is a circle of radius = square root of 2

    Question 307
    CBSEENMA12036044

    The distance of the point (1,0,2) from the point of intersection of the line fraction numerator straight x minus 2 over denominator 3 end fraction space equals space fraction numerator straight y plus 1 over denominator 4 end fraction space equals space fraction numerator straight z minus 2 over denominator 12 end fraction and the plane x-y +z = 16 is

    • 2 square root of 14
    • 8

    • 3 square root of 21
    • 13

    Solution

    D.

    13

    Given equation of line 
    fraction numerator straight x minus 2 over denominator 3 end fraction space equals space fraction numerator straight y plus 1 over denominator 4 end fraction space equals space fraction numerator straight z minus 2 over denominator 12 end fraction space equals space straight lambda space.. space left parenthesis straight i right parenthesis
    and the equation of the plane is 
    x-y+z = 16 ... (ii)
    Any point on the line (i) is
    (3λ +2, 4λ-1, 12λ +2) = 16
    11λ + 5 = 16
    11λ =11
    λ =1
    therefore, Point of intersection is (5,3,14)
    Now, distance between the points (1,0,2) and (5,3,2)
    space equals square root of left parenthesis 5 minus 1 right parenthesis squared left parenthesis 3 minus 0 right parenthesis squared plus left parenthesis 14 minus 2 right parenthesis squared end root
equals space square root of 16 plus 9 plus 144 end root
equals space square root of 169 space equals space 13

    Question 308
    CBSEENMA12036045

    The equation of the plane containing the line 2x-5y +z = 3, x +y+4z = 5 and parallel to the plane x +3y +6z =1 is

    • 2x + 6y + 12z = 13

    • x+3y+6z = -7

    • x+3y +6z = 7

    • 2x+ 6y+12z = - 13

    Solution

    C.

    x+3y +6z = 7

    Let equation of plane containing the lines 2x- 5y +z = 3 and x+y+4z = 5 be
    (2x-5y+z-3) + λ(x+y+4z-5) = 0
    ⇒ (2+λ)x + (λ-5)y + (4λ + 1)z -3 -5λ =0... (i)
    This plane is parallel to the plane x +3y +6z = 1
    therefore space fraction numerator 2 plus straight lambda over denominator 1 end fraction space equals space fraction numerator straight lambda minus 5 over denominator 3 end fraction space equals space fraction numerator 4 straight lambda plus 1 over denominator 6 end fraction
    On taking first two equalities, we get
    6λ -30 = 3 + 12λ
    -6λ = 33
    λ = - 11/2
    So, the equation of required plane is
    open parentheses 2 minus 11 over 2 close parentheses space straight x space plus open parentheses fraction numerator negative 11 over denominator 5 end fraction minus 5 close parentheses straight y space plus open parentheses fraction numerator negative 44 over denominator 2 end fraction plus 1 close parentheses straight z space minus 3 space plus space 5 straight x space 11 over 2 space equals space 0
rightwards double arrow negative 7 over 2 space straight x minus 21 over 2 straight y minus 42 over 2 straight z plus 49 over 2 space equals space 0
rightwards double arrow space straight x space plus space 3 straight y space plus 6 straight z minus 7 space equals space 0

    Question 309
    CBSEENMA12036052

    The integral integral open parentheses 1 plus straight x space minus 1 over straight x close parentheses straight e to the power of straight x plus 1 over straight x end exponent dx is equal to 

    • left parenthesis straight x minus 1 right parenthesis straight e to the power of straight x plus 1 over straight x space plus straight C end exponent
    • xe to the power of straight x plus 1 over straight x end exponent plus straight C
    • left parenthesis straight x plus 1 right parenthesis straight e to the power of straight x plus 1 over straight x space plus straight C end exponent
    • negative xe to the power of straight x plus 1 over straight x end exponent plus straight C

    Solution

    B.

    xe to the power of straight x plus 1 over straight x end exponent plus straight C integral open parentheses 1 plus straight x minus 1 over straight x close parentheses straight e to the power of straight x plus 1 over straight x dx end exponent
space equals space integral straight e to the power of straight x plus 1 half end exponent dx space plus integral straight x open parentheses 1 minus 1 over straight x squared close parentheses straight e to the power of straight x space plus 1 over straight x end exponent dx
equals space integral straight e to the power of straight x plus 1 over straight x end exponent dx space plus xe to the power of straight x plus 1 over straight x end exponent minus integral straight e to the power of straight x plus 1 over straight x end exponent dx
space equals space straight e to the power of straight x plus 1 over straight x dx end exponent space plus xe to the power of straight x plus 1 over straight x end exponent minus integral straight e to the power of straight x plus 1 over straight x end exponent dx
open square brackets because space integral straight e to the power of straight x plus 1 over straight x end exponent dx space plus xe to the power of straight x plus 1 over straight x end exponent minus integral straight e to the power of straight x plus 1 over straight x end exponent dx space equals space straight e to the power of straight x plus 1 over straight x end exponent close square brackets
equals space straight e to the power of straight x plus 1 over straight x end exponent dx space plus xe to the power of straight x plus 1 over straight x end exponent minus integral ex to the power of straight x plus 1 over straight x end exponent dx
space equals space xe to the power of straight x plus 1 over straight x end exponent space plus straight C
    Question 310
    CBSEENMA12036053

    The Integral integral subscript 0 superscript straight pi square root of 1 plus 4 space sin squared straight x over 2 minus 4 sin straight x over 2 dx end root is equal to

    • π-4

    • fraction numerator 2 space straight pi over denominator 3 end fraction minus 4 minus 4 square root of 3
    • 4 square root of 3 minus 4
    • 4 square root of 3 minus 4 minus 4 square root of 3

    Solution

    D.

    4 square root of 3 minus 4 minus 4 square root of 3

    By using the formula, vertical line straight x minus straight a vertical line space equals open curly brackets table attributes columnalign left end attributes row cell straight x minus straight a comma space space space space space space space space space straight x greater or equal than straight a end cell row cell negative left parenthesis straight x minus straight a right parenthesis comma space space space straight x less than straight a end cell end table close
    It breaks given integral in two parts and then integrates separately.
    integral subscript 0 superscript straight x square root of open parentheses 1 minus 2 sin straight x over 2 close parentheses squared end root dx space equals space integral subscript 0 superscript straight pi vertical line 1 minus 2 space sin straight x over 2 vertical line dx
equals integral subscript 0 superscript straight pi over 3 end superscript open parentheses 1 minus 2 space sin space straight x over 2 close parentheses dx space minus integral subscript straight pi over 3 end subscript superscript straight pi open parentheses 1 minus 2 space sin space straight x over 2 close parentheses dx
equals space open parentheses straight x plus 4 space cos space straight x over 2 close parentheses subscript 0 superscript straight pi over 3 end superscript space minus space open parentheses straight x plus 4 space cos space straight x over 2 close parentheses subscript straight pi over 3 end subscript superscript straight pi
equals space 4 square root of 3 space minus 4 minus straight pi over 3

    Question 311
    CBSEENMA12036058

    Distance between two parallel planes 2x + y + 2z = 8 and 4x + 2y + 4z + 5 = 0 is

    • 3/2

    • 5/2

    • 7/2

    • 9/2

    Solution

    C.

    7/2

    2x+y+2z-8 =0
    2x+y+2z+5/2 = 0
    Distance between two parallel planes
    equals space fraction numerator vertical line straight d subscript 1 minus straight d subscript 2 vertical line over denominator square root of straight a squared plus straight b squared plus straight c squared end root end fraction space equals space open vertical bar fraction numerator negative 8 minus begin display style 5 over 2 end style over denominator square root of 2 squared plus 1 squared plus 2 squared end root end fraction close vertical bar space equals space fraction numerator begin display style 21 over 2 end style over denominator 3 end fraction space equals space 7 over 2

    Question 314
    CBSEENMA12036062

    If ∫f x dx =Ψ (x),then ∫x5 f(x3)dx is equal to

    • 1 third space open square brackets straight x cubed straight psi left parenthesis straight x cubed right parenthesis minus integral straight x squared space straight psi left parenthesis straight x cubed right parenthesis dx close square brackets space plus straight C
    • 1 third space straight x cubed straight psi left parenthesis straight x cubed right parenthesis minus 3 integral straight x squared space straight psi left parenthesis straight x cubed right parenthesis dx space plus straight C
    • 1 third straight x cubed straight psi left parenthesis straight x cubed right parenthesis minus integral straight x squared space straight psi left parenthesis straight x cubed right parenthesis dx space plus space straight C
    • 1 third open square brackets straight x cubed straight psi left parenthesis straight x cubed right parenthesis minus integral straight x squared space straight psi left parenthesis straight x cubed right parenthesis dx close square brackets plus space straight C

    Solution

    C.

    1 third straight x cubed straight psi left parenthesis straight x cubed right parenthesis minus integral straight x squared space straight psi left parenthesis straight x cubed right parenthesis dx space plus space straight C

    Given, ∫f(x) dx = Ψ (x)
    Let l = ∫x5f(x3)dx
    Put x3 = t 
    ⇒ x2dx = dt/3 ...... (i) 
    From space equ space left parenthesis straight i right parenthesis
therefore space l space equals space 1 third integral straight t space straight f left parenthesis straight t right parenthesis space dt space equals space 1 third left square bracket straight x cubed space straight psi left parenthesis straight x cubed right parenthesis minus 3 integral straight x squared straight psi left parenthesis straight x cubed right parenthesis dx right square bracket space plus straight C space
equals space 1 third space straight x cubed space straight psi left parenthesis straight x cubed right parenthesis space minus integral straight x squared space straight psi left parenthesis straight x cubed right parenthesis space dx space plus space straight C space

    Question 316
    CBSEENMA12036070

    If the integral integral fraction numerator 5 space tan space straight x over denominator tan space straight x minus 2 end fraction straight d space straight x space equals space straight x
space plus space straight a space log space vertical line space sin space straight x minus space 2 space cos space straight x vertical line space plus space straight k comma  then an equal to 

    • -1

    • -2

    • 1

    • 2

    Solution

    D.

    2

    integral fraction numerator 5 space tan space straight x over denominator tan space straight x minus 2 end fraction straight d space straight x space equals space straight x space plus space straight a space log space vertical line space sin space straight x minus space 2 space cos space straight x vertical line space plus space straight k comma space... space left parenthesis straight i right parenthesis
    Now, let us assume that I,
    straight I space equals integral fraction numerator 5 space tan space straight x over denominator tan space straight x minus 2 end fraction straight d space straight x
    Multiplying by cos x in numerator and denominator, we get
    straight I space equals space integral fraction numerator 5 space sin space straight x over denominator sin space straight x minus 2 space cos space straight x end fraction straight d space straight x
    This special integration requires special substitution of type
    N' = A (D') +straight B space open parentheses fraction numerator dD apostrophe over denominator dx end fraction close parentheses
    ⇒ Let 5 sin x = (A + 2B) sin x + (B- 2A) cos x
    Comapring the coefficients of sin x and cosx, 
    we get
    A +2B =5 and B- 2A = 0
    Solving the above two equations in A and B
    we get
    A = 1 an B= 2
    ⇒ 5 sin x = ( sin x - 2 cos x)+ 2 (cos x + 2 sin x)
    rightwards double arrow space straight I space equals space integral fraction numerator 5 space sin space straight x over denominator sin space straight x minus space 2 space cos space straight x end fraction dx
space equals space integral fraction numerator sin space straight x minus space 2 space cos space straight x right parenthesis space plus space 2 space left parenthesis cos space straight x space plus 2 space sin space straight x right parenthesis space dx over denominator left parenthesis sin space straight x minus 2 space cos space straight x right parenthesis end fraction
rightwards double arrow space straight I space equals space integral fraction numerator left parenthesis sin space straight x minus 2 space cos space straight x right parenthesis plus space 2 space left parenthesis cos space straight x space plus 2 space sin space straight x right parenthesis over denominator sin space straight x minus space 2 cos space straight x end fraction space dx
rightwards double arrow space straight I space equals space integral fraction numerator sin space straight x minus space 2 space cos space straight x over denominator sin space straight x minus space 2 space cos space straight x end fraction dx space plus space 2 space integral fraction numerator left parenthesis cos space straight x space plus 2 space sin space straight x right parenthesis over denominator left parenthesis sin space straight x minus 2 space cos space straight x right parenthesis end fraction dx
rightwards double arrow space straight I space equals integral space 1 space dx space plus space 2 space integral fraction numerator straight d left parenthesis sin space straight x minus 2 space cos space straight x right parenthesis over denominator left parenthesis sin space straight x minus space 2 space cos space straight x right parenthesis space end fraction
rightwards double arrow space straight I space space equals space straight x space plus 2 space log space vertical line sin space straight x minus space 2 space cos space straight x right parenthesis vertical line space plus straight k space... space left parenthesis ii right parenthesis
    where k is the constant of integration. Now, by comparing the value of l in eq. (i) and (ii) we get a = 2
    Question 318
    CBSEENMA12036077

    If g(x) = integral subscript 0 superscript straight x cos space 4 straight t space dt comma then g(x +π) equals

    • g(x)/g(π)

    • g(x) +g(π)

    • g (x) - g(π)

    • g(x). g(π)

    Solution

    B.

    g(x) +g(π)

    C.

    g (x) - g(π)

    Integral straight g space left parenthesis straight x right parenthesis space equals space integral subscript 0 superscript straight x space cos space 4 straight t. dt
    To find g(x+π) in terms of g(x) of g(π)
    straight g left parenthesis straight x right parenthesis space equals space integral subscript 0 superscript straight x space cos space 4 straight t space dt
rightwards double arrow space straight g left parenthesis straight x plus space straight pi right parenthesis space equals space integral subscript straight t space equals 0 end subscript superscript straight t space equals space straight x plus straight pi end superscript space cos space 4 straight t space dt
equals space integral subscript 0 superscript straight x space cos space 4 straight t space dt space plus space integral subscript straight x superscript straight x plus straight pi end superscript space cos space 4 straight t space dt
equals space straight g left parenthesis straight x right parenthesis space plus straight I subscript 1
straight l subscript 1 space equals space integral subscript straight x superscript straight x plus straight pi space end superscript space cos space 4 straight t space dt
equals integral subscript 0 superscript straight pi space cos space 4 straight t space dt
space equals space straight g left parenthesis straight pi right parenthesis
straight g left parenthesis straight x plus straight pi right parenthesis space equals space straight g left parenthesis straight x right parenthesis space plus straight g left parenthesis straight pi right parenthesis
But space the space value space of space straight I subscript 1 space is space zero
rightwards double arrow space straight g left parenthesis straight x plus straight pi right parenthesis space equals space straight g left parenthesis straight x right parenthesis minus straight g left parenthesis straight pi right parenthesis

    Question 319
    CBSEENMA12036080

    The value of integral subscript 0 superscript 1 fraction numerator 18 space log space left parenthesis 1 plus straight x right parenthesis over denominator 1 plus straight x squared end fraction space dx is

    • straight pi over 8 space log space 2
    • straight pi over 2 space log space 2
    • log 2

    • π log 2

    Solution

    D.

    π log 2

    straight I space equals integral subscript 0 superscript 1 fraction numerator 18 space log space left parenthesis 1 plus straight x right parenthesis over denominator 1 plus straight x squared end fraction d x 
    put x = tan θ
    ⇒ dx = sec2 θdθ
    When x = 0 
    ⇒ tan θ = 0 
    ∴ θ = 0
    When x = 1 = tan θ
    θ = π/4
    straight I space equals integral subscript 0 superscript 1 fraction numerator 18 space log space left parenthesis 1 plus tan space straight theta right parenthesis over denominator 1 plus tan squared space straight theta end fraction sec squared straight theta space dθ
straight I space equals space 8 integral subscript 0 superscript straight pi divided by 4 end superscript log space left parenthesis 1 plus space tan space straight theta right parenthesis space dθ space.... space left parenthesis straight i right parenthesis space
Using space space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a space straight f left parenthesis straight a minus straight x right parenthesis space dx comma space we space get
straight I space equals space 8 space integral subscript 0 superscript straight pi divided by 4 end superscript space log space open curly brackets 1 plus space tan space open parentheses straight pi over 4 minus straight theta close parentheses close curly brackets dθ
space equals space straight I space equals space 8 space integral subscript 0 superscript straight pi divided by 4 end superscript space log space open curly brackets 1 plus space fraction numerator 1 minus space tan space straight theta over denominator 1 plus space tan space straight theta end fraction close curly brackets dθ
equals space 8 space integral subscript 0 superscript straight pi divided by 4 end superscript space log space open curly brackets 1 plus space fraction numerator 2 over denominator 1 plus space tan space straight theta end fraction close curly brackets dθ space... space left parenthesis ii right parenthesis
Adding space eqs space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis thin space we space get
2 straight I space space equals space 8 space space integral subscript 0 superscript straight pi divided by 4 end superscript space log space 2 space dθ space equals space 4. space log space left parenthesis straight theta right parenthesis subscript 0 superscript straight pi divided by 4 end superscript
equals space 4 space log space 2. space open parentheses straight pi over 4 minus 0 close parentheses space equals space straight pi space log space 2 
    Question 320
    CBSEENMA12036087

    If the angle between the line x =fraction numerator straight y minus 1 over denominator 2 end fraction space equals space fraction numerator straight z minus 3 over denominator straight lambda end fraction and the plane x + 2y + 3z = 4 is cos-1 square root of 5 over 14 end root then λ equal

    • 2/3

    • 3/2

    • 2/5

    • 3/5

    Solution

    A.

    2/3

    fraction numerator straight x minus 0 over denominator 1 end fraction space equals space fraction numerator straight y minus 1 over denominator 2 end fraction space equals space fraction numerator straight z minus 3 over denominator straight lambda end fraction space... space left parenthesis 1 right parenthesis
    x + 2y + 3z = 4 ....... (2)

    Angle between the line and plane is
    cos space left parenthesis 90 minus space straight theta right parenthesis space equals space fraction numerator straight a subscript 1 straight a subscript 2 space plus straight b subscript 1 straight b subscript 2 space plus space straight c subscript 1 straight c subscript 2 over denominator square root of straight a subscript 1 superscript 2 plus straight b subscript 1 superscript 2 plus straight c subscript 1 superscript 2 end root space square root of straight a subscript 2 superscript 2 plus straight b subscript 2 superscript 2 plus straight c subscript 2 superscript 2 end root end fraction
rightwards double arrow space sin space straight theta space equals space fraction numerator 1 space plus space 4 space plus space 3 straight lambda over denominator square root of 14 space straight x space square root of 5 space plus space straight lambda squared end root end fraction space equals space fraction numerator 5 space plus space 3 straight lambda over denominator square root of 14 space straight x space end root square root of 5 space plus space straight lambda squared end root end fraction space... space left parenthesis 3 right parenthesis
    But given that angle between line and plane is

    rightwards double arrow space sin space straight theta space equals space fraction numerator 3 over denominator square root of 14 end fraction
therefore space from space left parenthesis 3 right parenthesis
fraction numerator 3 over denominator square root of 14 end fraction space equals space fraction numerator space 5 space plus space 3 straight lambda over denominator square root of 14 space end root space straight x square root of space 5 space plus straight lambda squared end root end fraction
rightwards double arrow space 9 space left parenthesis 5 space plus space straight lambda squared right parenthesis space equals space 25 space plus space 9 straight lambda squared space plus space 30 space straight lambda
30 space straight lambda space equals space 20
straight lambda space equals space 2 divided by 3
    Question 323
    CBSEENMA12036099

    Statement-1 : The point A(1, 0, 7) is the mirror image of the point B(1, 6, 3) in the line: straight x over 1 space equals space fraction numerator straight y minus 1 over denominator 2 end fraction space equals space fraction numerator straight z minus 2 over denominator 3 end fraction
    Statement-2: The line:straight x over 1 space equals space fraction numerator straight y minus 1 over denominator 2 end fraction space equals space fraction numerator straight z minus 2 over denominator 3 end fraction  bisects the line segment joining A(1, 0, 7) and B(1, 6, 3).

    • Statement-1 is true, Statement-2 is true; Statement-2 is a correct explanation for Statement-1. 

    • Statement-1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1. 

    • Statement-1 is true, Statement-2 is false.

    • Statement-1 is false, Statement-2 is true.

    Solution

    B.

    Statement-1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1. 


    Mid- point of AB ≡ M(1,3,5)
    M lies on line
    Direction ratios of AB is < 0, 6, - 4 >
    Direction ratios of given line is < 1, 2, 3 >
    As AB is perpendicular to line
    ∴ 0.1 + 6.2 - 4.3 = 0

    Question 324
    CBSEENMA12036103

    There are two urns. Urn A has 3 distinct red balls and urn B has 9 distinct blue balls. From each urn two balls are taken out at random and then transferred to the other. The number of ways in which this can be done is

    • 3

    • 36

    • 66

    • 108

    Solution

    D.

    108

    The number  of ways in which two balls from urn A and two balls from urn B can be selected
     = 3C2 x 9C2 =  3x 36  = 108

    Question 326
    CBSEENMA12036114

    An urn contains nine balls of which three are red, four are blue and two are green. Three balls are drawn at random without replacement from the urn. The probability that the three balls have different colours is

    • 1/3

    • 2/7

    • 1/21

    • 2/23

    Solution

    B.

    2/7

    Number of ways to select exactly one ball 

    =3C1 × 4C1 × 2C1
    Number of ways to select 3 balls out of 9 is
    9C3
    Required probabilityfraction numerator 3 space straight x space 4 space straight x space 2 over denominator left parenthesis to the power of 9 straight C subscript 3 right parenthesis end fraction space equals space 2 over 7

    Question 327
    CBSEENMA12036117

    The line L given by straight x over 5 space plus straight y over straight b space equals space 1 passes through the point (13, 32). The line K is parallel to L and has the equation straight x over straight c space plus straight y over 3 space equals space 1 . Then the distance
    between L and K is

    • fraction numerator 23 over denominator square root of 15 end fraction
    • square root of 17
    • fraction numerator 17 over denominator square root of 15 end fraction
    • fraction numerator 23 over denominator square root of 17 end fraction

    Solution

    D.

    fraction numerator 23 over denominator square root of 17 end fraction

    Since, the line L is passing through the point (13,32)
    Therefore,
    13 over 5 space plus 32 over straight b space equals space 1
rightwards double arrow space 32 over straight b space equals space minus 8 over 5
rightwards double arrow space straight b space equals space minus 20
    The line K is parallel to the line L then its equation must be
    straight x over 5 minus straight y over 20 space equals straight a space
Or
fraction numerator straight x over denominator 5 straight a end fraction minus fraction numerator straight y over denominator 20 straight a end fraction space equals space 1
On space comparing space with space straight x over straight c space plus straight y over 3 space equals space 1 comma space we space straight g space et
20 straight a space equals space minus space 3 comma space straight c space equals 5 straight a space equals space minus 3 over 4
Hence comma space the space distance space between space lines
fraction numerator vertical line straight a minus 1 vertical line over denominator square root of begin display style 1 over 25 plus 1 over 400 end style end root end fraction space equals space fraction numerator open vertical bar begin display style fraction numerator negative 3 over denominator 20 end fraction minus 1 end style close vertical bar over denominator square root of begin display style 17 over 400 end style end root end fraction space equals space fraction numerator 23 over denominator square root of 17 end fraction

    Question 329
    CBSEENMA12036121

    Let k be an integer such that triangle with vertices (k, –3k), (5, k) and (–k, 2) has area 28 sq. units. Then the orthocentre of this triangle is at the point 

    • open parentheses 2 comma 1 half close parentheses
    • open parentheses 2 comma negative 1 half close parentheses
    • open parentheses 1 comma negative 3 over 2 close parentheses
    • open parentheses 1 comma 3 over 2 close parentheses

    Solution

    A.

    open parentheses 2 comma 1 half close parentheses

    We have,
    1 half open vertical bar table row straight k cell negative 3 straight k end cell 1 row 5 straight k 1 row cell negative straight k end cell 2 1 end table close vertical bar space equals space 28

    ⇒ 5k2 + 13k – 46 = 0
    or
    5k2 + 13k + 66 = 0 (no real solution exist)
    ∴ k =–23/5
    or k = 2
    k is an integer, so k =2
    As 
    Therefore (2, 1/2)

     

    Question 331
    CBSEENMA12036125

    The normal to the curve y(x – 2)(x – 3) = x + 6 at the point where the curve intersects the y-axis passes through the point

    • open parentheses fraction numerator 1 over denominator 2 comma end fraction 1 third close parentheses
    • open parentheses fraction numerator 1 over denominator 2 comma end fraction 1 half close parentheses
    • open parentheses negative fraction numerator 1 over denominator 2 comma end fraction minus 3 over 2 close parentheses

    Solution

    C.

    open parentheses fraction numerator 1 over denominator 2 comma end fraction 1 half close parentheses space space straight y equals space fraction numerator straight x space plus space 6 over denominator left parenthesis straight x space minus 2 right parenthesis left parenthesis straight x minus 3 right parenthesis end fraction
Point space of space intersection space with space straight y space minus space axis space left parenthesis 0 comma 1 right parenthesis
straight y apostrophe space equals space fraction numerator left parenthesis straight x squared space minus 5 straight x space plus 6 right parenthesis space left parenthesis 1 right parenthesis space minus space left parenthesis straight x plus space 6 right parenthesis left parenthesis 2 straight x minus 5 right parenthesis over denominator left parenthesis straight x squared minus 5 straight x space plus 6 right parenthesis squared end fraction

    y'= 1 at point (0, 1)
    ∴ Slope of normal is –1
    Hence equation of normal is x + y = 1
    ∴ (1/2, 1/2)satisfy it.

    Question 332
    CBSEENMA12036127

    The integral  integral subscript straight pi over 4 end subscript superscript fraction numerator 3 straight pi over denominator 4 end fraction end superscript fraction numerator dx over denominator 1 plus space cos space straight x end fractionis equal to

    • -1

    • -2

    • 2

    • 4

    Solution

    C.

    2

    straight I space equals integral subscript straight pi over 4 end subscript superscript fraction numerator 3 straight pi over denominator 4 end fraction end superscript fraction numerator dx over denominator 1 plus space cos space straight x end fraction space space..... space left parenthesis 1 right parenthesis
I space equals integral subscript straight pi over 4 end subscript superscript fraction numerator 3 straight pi over denominator 4 end fraction end superscript fraction numerator dx over denominator 1 minus space cos space straight x end fraction space space..... space left parenthesis 2 right parenthesis
Adding space left parenthesis 1 right parenthesis space and space left parenthesis 2 right parenthesis
2 straight I space equals integral subscript straight pi over 4 end subscript superscript fraction numerator 3 straight pi over denominator 4 end fraction end superscript fraction numerator 2 over denominator sin squared space straight x end fraction dx
straight I space equals integral subscript straight pi over 4 end subscript superscript fraction numerator 3 straight pi over denominator 4 end fraction end superscript space cosec squared space straight x space dx
straight I space equals space minus space left parenthesis cot space straight x space right parenthesis subscript straight pi divided by 4 end subscript superscript 3 straight pi divided by 4 end superscript space equals 2 space space
    Question 337
    CBSEENMA12036171

    The value of square root of 2 space integral fraction numerator sin space straight x space dx over denominator sin space open parentheses straight x minus begin display style straight pi over 4 end style close parentheses end fraction space is

    • space straight x plus space log open vertical bar cos space open parentheses straight x minus straight pi over 4 close parentheses close vertical bar space plus space straight C
    • straight x space minus log space open vertical bar sin space open parentheses straight x minus straight pi over 4 close parentheses close vertical bar space plus straight c
    • straight x space plus space log space open vertical bar sin space open parentheses straight x minus straight pi over 4 close parentheses close vertical bar space plus straight c
    • straight x space plus space log space open vertical bar cos space open parentheses straight x minus straight pi over 4 close parentheses close vertical bar space plus straight c

    Solution

    C.

    straight x space plus space log space open vertical bar sin space open parentheses straight x minus straight pi over 4 close parentheses close vertical bar space plus straight c square root of 2 space integral fraction numerator sin space straight x space dx over denominator sin space open parentheses straight x minus begin display style straight pi over 4 end style close parentheses end fraction space equals space square root of 2 integral fraction numerator sin space open parentheses straight x minus begin display style straight pi over 4 end style plus begin display style straight pi over 4 end style close parentheses dx over denominator sin space open parentheses straight x minus space begin display style straight pi over 4 end style close parentheses end fraction
space equals space square root of 2 space integral open parentheses cos space straight pi over 4 space plus space cot space open parentheses straight x minus space straight pi over 4 close parentheses space sin space straight pi over 4 close parentheses space dx
space equals space integral space dx space plus space integral cot space open parentheses straight x space minus space straight pi over 4 close parentheses dx
equals space straight x space plus space In space open vertical bar sin space open parentheses straight x minus straight pi over 4 close parentheses close vertical bar space plus straight c
    Question 338
    CBSEENMA12036188

    let space straight F left parenthesis straight x right parenthesis space equals space straight f left parenthesis straight x right parenthesis space plus space straight f space open parentheses 1 over straight x close parentheses comma space where space straight f left parenthesis straight x right parenthesis space equals space integral subscript 1 superscript straight x fraction numerator log space straight t over denominator 1 plus straight t end fraction dt. Then F(e) equals
    • 1/2

    • 1

    • 2

    • 0

    Solution

    A.

    1/2

    straight f left parenthesis straight x right parenthesis space equals space integral subscript 1 superscript straight x fraction numerator log space straight t over denominator 1 space plus straight t end fraction space dt
straight F left parenthesis straight e right parenthesis space equals space straight f left parenthesis straight e right parenthesis space plus space straight f open parentheses 1 over straight e close parentheses
straight F left parenthesis straight e right parenthesis space equals space integral subscript 1 superscript straight e space fraction numerator log space straight t over denominator 1 plus straight t end fraction dt space plus integral subscript 1 superscript 1 divided by straight e end superscript fraction numerator log space straight t over denominator 1 plus straight t end fraction dt
space equals space integral subscript 1 superscript straight e fraction numerator log space straight t over denominator 1 plus straight t end fraction space plus integral subscript 1 superscript straight e fraction numerator log space straight t over denominator straight t left parenthesis 1 plus straight t right parenthesis end fraction dt
space equals space integral subscript 1 superscript straight e space fraction numerator log space straight t over denominator straight t end fraction space dt space equals space 1 half
    Question 339
    CBSEENMA12036195

    The value of the integral,integral subscript 3 superscript 6 fraction numerator square root of straight x over denominator square root of 9 minus straight x end root plus square root of straight x end fraction dx is

    • 1/2

    • 3/2

    • 2

    • 1

    Solution

    B.

    3/2

    straight I space equals space integral subscript 3 superscript 6 fraction numerator square root of straight x over denominator square root of 9 minus straight x end root plus square root of straight x end fraction dx
straight I space equals space integral subscript 3 superscript 6 fraction numerator square root of 9 minus straight x end root over denominator square root of 9 minus straight x end root plus square root of straight x end fraction dx
2 straight I space equals space integral subscript 3 superscript 6 dx space equals space 3
rightwards double arrow straight I space equals space 3 over 2
    Question 340
    CBSEENMA12036201

    integral subscript 0 superscript straight pi space xf space left parenthesis sin space straight x space right parenthesis space dx is equal to
    • straight pi integral subscript 0 superscript straight pi space straight f left parenthesis cos space straight x right parenthesis space dx
    • straight pi integral subscript 0 superscript straight pi space straight f left parenthesis sin space straight x right parenthesis space dx
    • straight pi over 2 integral subscript 0 superscript straight pi space straight f left parenthesis cos space straight x right parenthesis space dx
    • straight pi integral subscript 0 superscript straight pi divided by 2 end superscript space straight f left parenthesis cos space straight x right parenthesis space dx

    Solution

    D.

    straight pi integral subscript 0 superscript straight pi divided by 2 end superscript space straight f left parenthesis cos space straight x right parenthesis space dx straight I space equals space integral subscript 0 superscript straight pi xf space left parenthesis sin space straight x right parenthesis space dx
equals space integral subscript 0 superscript straight pi left parenthesis straight pi minus straight x right parenthesis space straight f left parenthesis sin space straight x right parenthesis space dx
space equals integral subscript 0 superscript straight pi straight f left parenthesis sin space straight x right parenthesis space dx space minus straight l
2 straight l space equals space integral subscript 0 superscript straight pi straight f left parenthesis sin space straight x right parenthesis space dx
straight l space equals space straight pi over 2 integral subscript 0 superscript straight pi space straight f left parenthesis sin space straight x right parenthesis space dx
space equals straight pi space integral subscript 0 superscript straight pi divided by 2 end superscript space straight f space left parenthesis sin space straight x right parenthesis space dx
equals straight pi integral subscript 0 superscript straight pi divided by 2 end superscript space straight f left parenthesis cos space straight x right parenthesis space dx
    Question 341
    CBSEENMA12036203

    integral subscript negative 3 straight pi divided by 2 end subscript superscript negative straight pi divided by 2 end superscript open square brackets open parentheses straight x plus straight pi close parentheses cubed plus space cos space left parenthesis straight x space plus 3 straight pi right parenthesis close square brackets dx space is space equal space to
    • straight pi to the power of 4 over 32
    • straight pi to the power of 4 over 32 space plus space pi over 2
    • pi over 2
    • pi over 4 minus 1

    Solution

    C.

    pi over 2 straight I space equals space integral subscript negative 3 straight pi divided by 2 end subscript superscript straight pi divided by 2 end superscript open square brackets open parentheses straight x plus straight pi close parentheses cubed space plus space cos squared space left parenthesis straight x space plus 3 straight pi right parenthesis close square brackets dx
space Put space straight x space plus straight pi space equals space straight t
straight I space equals space integral subscript negative straight pi divided by 2 end subscript superscript straight pi divided by 2 end superscript space open square brackets straight t cubed space plus space cos squared straight t close square brackets dt
space equals space 2 integral subscript 0 superscript straight pi divided by 2 end superscript space cos squared straight t space dt
space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space left parenthesis 1 plus space cos space 2 straight t right parenthesis dt space equals space straight pi over 2 plus 0
    Question 342
    CBSEENMA12036229

    integral space open curly brackets fraction numerator left parenthesis log space straight x minus 1 right parenthesis over denominator 1 plus left parenthesis log space straight x right parenthesis squared end fraction close curly brackets squared space dx space is space equal space to
    • fraction numerator log space straight x over denominator left parenthesis log space straight x right parenthesis squared plus 1 end fraction plus space straight C
    • fraction numerator straight x over denominator straight x plus 1 end fraction space plus straight C
    • fraction numerator xe to the power of straight x over denominator 1 plus straight x squared end fraction plus straight C
    • fraction numerator straight x over denominator left parenthesis log space straight x right parenthesis squared space plus space 1 end fraction plus space straight C

    Solution

    D.

    fraction numerator straight x over denominator left parenthesis log space straight x right parenthesis squared space plus space 1 end fraction plus space straight C integral fraction numerator left parenthesis log space straight x minus 1 right parenthesis squared over denominator left parenthesis 1 plus left parenthesis log space straight x right parenthesis squared right parenthesis squared end fraction dx
space equals space integral space open square brackets fraction numerator 1 over denominator left parenthesis 1 plus left parenthesis log space straight x right parenthesis squared right parenthesis end fraction minus fraction numerator 2 space log space straight x over denominator left parenthesis 1 plus left parenthesis log space straight x right parenthesis squared right parenthesis squared end fraction close square brackets space dx
space equals integral open square brackets fraction numerator straight e to the power of straight t over denominator 1 plus straight t squared end fraction minus fraction numerator 2 straight t space straight e to the power of straight t over denominator left parenthesis 1 plus straight t squared right parenthesis squared end fraction close square brackets space dt space put space log space straight x space equals space straight t
rightwards double arrow space dx space equals straight e to the power of straight t space dt
integral straight e to the power of straight t space open square brackets fraction numerator 1 over denominator 1 plus straight t squared end fraction minus fraction numerator 2 straight t over denominator left parenthesis 1 plus straight t squared right parenthesis squared end fraction close square brackets dt
space equals space fraction numerator straight e to the power of straight t over denominator 1 plus straight t squared end fraction space plus straight c equals space fraction numerator straight x over denominator 1 plus space left parenthesis log space straight x right parenthesis squared end fraction space plus straight c
    Question 345
    CBSEENMA12036240

    The value of integral subscript negative straight pi end subscript superscript straight pi space fraction numerator cos squared space straight x over denominator 1 plus space straight a to the power of straight x end fraction space dx comma space straight a greater than 0 space is

    • a π

    • π/2

    • π/a

    Solution

    B.

    π/2

    integral subscript negative straight pi end subscript superscript straight pi space fraction numerator cos squared over denominator 1 plus straight a to the power of straight x end fraction space dx space equals space integral subscript 0 superscript straight pi space cos squared space straight x space dx space equals space straight pi over 2
    Question 346
    CBSEENMA12036261

    If integral space fraction numerator sin space straight x over denominator sin space left parenthesis straight x minus straight alpha right parenthesis end fraction space dx space equals space Ax space plus space straight B space log space sin space left parenthesis straight x minus straight alpha right parenthesis space plus straight C comma space space then space value space left parenthesis straight A comma space straight B right parenthesis is

    • (sinα, cosα)

    • (cosα, sinα)

    • (- sinα, cosα)

    • (- cosα, sinα)

    Solution

    B.

    (cosα, sinα)

    Put x – α = t
    rightwards double arrow space integral fraction numerator sin space left parenthesis straight alpha space plus straight t right parenthesis over denominator sin space straight t end fraction space dt space equals space sin space straight alpha space integral space cot space dt space plus space cos space straight alpha space integral dt
space equals space cos space straight alpha space left parenthesis straight x minus straight alpha right parenthesis space plus space sin space straight alpha space ln space vertical line sin space straight t vertical line space plus straight c
straight A space equals space cos space straight alpha space comma space straight B space equals space sin space straight alpha

    Question 347
    CBSEENMA12036262

    integral fraction numerator dx over denominator cos space straight x space minus space sin space straight x end fraction is equal to
    • fraction numerator 1 over denominator square root of 2 end fraction space log space open vertical bar tan open parentheses straight x over 2 minus fraction numerator begin display style straight pi end style over denominator 8 end fraction close parentheses close vertical bar space plus straight C
    • fraction numerator 1 over denominator square root of 2 end fraction space log space open vertical bar cot open parentheses straight x over 2 close parentheses close vertical bar space plus straight C
    • fraction numerator 1 over denominator square root of 2 end fraction space log space open vertical bar tan open parentheses straight x over 2 minus fraction numerator 3 straight pi over denominator 8 end fraction close parentheses close vertical bar space plus straight C
    • fraction numerator 1 over denominator square root of 2 end fraction space log space open vertical bar tan open parentheses straight x over 2 plus fraction numerator 3 straight pi over denominator 8 end fraction close parentheses close vertical bar space plus straight C

    Solution

    D.

    fraction numerator 1 over denominator square root of 2 end fraction space log space open vertical bar tan open parentheses straight x over 2 plus fraction numerator 3 straight pi over denominator 8 end fraction close parentheses close vertical bar space plus straight C integral fraction numerator dx over denominator cos space straight x space minus space sin space straight x end fraction space equals space fraction numerator 1 over denominator square root of 2 end fraction integral fraction numerator 1 over denominator cos begin display style space end style begin display style open parentheses straight x space plus straight pi over 4 close parentheses end style end fraction space dx

equals space fraction numerator 1 over denominator square root of 2 end fraction integral space sec space open parentheses space straight x plus straight pi over 4 space close parentheses dx
space equals space fraction numerator 1 over denominator square root of 2 end fraction space log space open vertical bar space tan space open parentheses straight x over 2 space plus fraction numerator 3 straight pi over denominator 8 end fraction close parentheses close vertical bar space plus straight C
    Question 348
    CBSEENMA12036263

    The value of integral subscript negative 2 end subscript superscript 3 space vertical line 1 minus straight x squared vertical line dx space is

    • 28/7

    • 28/3

    • 7/3

    • 1/3

    Solution

    B.

    28/3

    integral subscript negative 2 end subscript superscript negative 1 end superscript space left parenthesis straight x squared minus 1 right parenthesis space dx space plus integral subscript negative 1 end subscript superscript 1 space left parenthesis 1 minus straight x squared right parenthesis space dx space plus integral subscript 1 superscript 3 left parenthesis straight x squared minus 1 right parenthesis space dx space equals space straight x cubed over 3 minus right enclose straight x subscript negative 2 end subscript superscript 1 space plus straight x minus right enclose straight x cubed over 3 end enclose subscript negative 1 end subscript superscript 1 plus straight x cubed over 3 minus right enclose right enclose straight x end enclose subscript 1 superscript 3
space equals space 28 over 3 space
    Question 349
    CBSEENMA12036264

    The value of integral subscript 0 superscript pi divided by 2 end superscript fraction numerator left parenthesis sin space x space plus space cos space x right parenthesis squared over denominator square root of 1 plus space sin space 2 x end root end fraction space d x space i s

    • 0

    • 1

    • 2

    • 3

    Solution

    C.

    2

    integral subscript 0 superscript straight pi divided by 2 end superscript fraction numerator left parenthesis sin space straight x space plus cos space straight x right parenthesis squared over denominator square root of left parenthesis sin space straight x space plus space cos space straight x right parenthesis squared end root end fraction space dx
space equals space integral subscript 0 superscript straight pi divided by 2 end superscript space left parenthesis sin space straight x space plus space cos space straight x right parenthesis space dx
space equals space vertical line minus space cos space straight x space plus space sin space straight x vertical line subscript 0 superscript straight pi divided by 2 end superscript space equals space 2
    Question 350
    CBSEENMA12036265

    Ifintegral subscript 0 superscript straight pi space xf space left parenthesis sin right parenthesis space dx space equals space straight A space integral subscript 0 superscript straight pi divided by 2 end superscript space straight f space left parenthesis sin space straight x right parenthesis space dx comma space then space straight A space is

    • 0

    • π

    • π/2

    • π/4

    Solution

    B.

    π

    Letlet space straight I space equals space integral subscript 0 superscript straight pi space xf space left parenthesis sin space straight x right parenthesis space dx
space equals space integral subscript 0 superscript straight pi space left parenthesis straight pi minus straight x right parenthesis space straight f space left parenthesis sin space straight x right parenthesis space dx
space equals space straight pi integral subscript 0 superscript straight pi space straight f space left parenthesis sin space straight x right parenthesis dx minus 1
left parenthesis since space straight f space left parenthesis 2 straight a minus straight x right parenthesis space equals space straight f left parenthesis straight x right parenthesis right parenthesis
rightwards double arrow space straight I space equals space straight pi integral subscript 0 superscript straight pi divided by 2 end superscript space straight f space left parenthesis sin right parenthesis space dx
rightwards double arrow space straight I subscript 2 divided by straight I subscript 1 space equals space 2
     =π

    Question 351
    CBSEENMA12036266

    If straight f left parenthesis straight x right parenthesis space equals space fraction numerator straight e to the power of straight x over denominator 1 plus straight e to the power of straight x end fraction. space straight I subscript 1 space equals space integral subscript straight f left parenthesis negative straight a right parenthesis end subscript superscript straight f left parenthesis straight a right parenthesis end superscript space xg open curly brackets straight x open parentheses 1 minus straight x close parentheses close curly brackets dx space and space straight I subscript 2 space equals space integral subscript straight f left parenthesis negative straight a right parenthesis end subscript superscript straight f left parenthesis straight a right parenthesis end superscript space straight g open curly brackets straight x open parentheses 1 minus straight x close parentheses close curly brackets dx then the value of I2/I1 is

    • 2

    • -2

    • 1

    • -1

    Solution

    A.

    2

    f(-a) + f(a) = 1
    straight I subscript 1 space equals space integral subscript straight f left parenthesis negative straight a right parenthesis end subscript superscript straight f left parenthesis straight a right parenthesis end superscript space xg left curly bracket straight x left parenthesis 1 minus straight x right parenthesis right curly bracket space dx
space equals space integral subscript straight f left parenthesis negative straight a right parenthesis end subscript superscript straight f left parenthesis straight a right parenthesis end superscript space left parenthesis 1 minus straight x right parenthesis space straight g space left curly bracket space straight x space left parenthesis 1 minus straight x right parenthesis right curly bracket dx
open parentheses because space integral subscript straight a superscript straight b space straight f space left parenthesis straight x right parenthesis space dx space equals space integral subscript straight a superscript straight b space straight f space left parenthesis straight a plus straight b minus straight x right parenthesis space dx close parentheses
2 straight I subscript 1 space equals space integral subscript straight f left parenthesis negative straight a right parenthesis end subscript superscript straight f left parenthesis straight a right parenthesis end superscript space straight g left curly bracket straight x space left parenthesis 1 minus straight x right parenthesis right curly bracket space dx space equals space straight I subscript 2
rightwards double arrow space straight I subscript 2 divided by straight I subscript 1 space space equals space 2

    Question 352
    CBSEENMA12036290

    The value of -π2π2sin2x1+2xdx is:

    • π/4

    • π/8

    • π/2

    Solution

    A.

    π/4

    I = -π2π2sin2 x dx1 + 2x ... (i)Also, I = -π2π22x sin2 x dx1 + 2x .... (ii)Adding (i) and (ii)2I = -π2π2 sin2 xdx2I = 20π2sin2 x dx I= 0π2sin2 xdx .... (iii)I =  0π2cos2 xdx .... (iv)Adding (iii) and (iv)2I =    0π2dx = π2I = π4

    Question 353
    CBSEENMA12036294

    The Integralsin2 x  cos2 x (sin5 x + cos3 x sin2 x + sin3 x cos2 x + cos 5x)2dx is equal to

    (where C is a constant of integration)

    • -11+ cot3 x  + C

    • 13(1 + tan3 x)  + C

    • -13(1 + tan3 x ) +C

    • 11+ cot3 x  + C

    Solution

    C.

    -13(1 + tan3 x ) +C

    I = sin2 x. cos2 x dx{(sin2 x  + cos2 x)(sin3 x + cos3 x)}2Divide numberator and denominator by cos6x I= tan2 x sec2 x dx(1 + tan3x)2Let tan3 x = z 3tan2 x. sec2 x dx = dz1 = 13dzz2 = -13z +C= -13(1 + tan3 x) +C

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