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Integrals

Question
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

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