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Vector Algebra

Question
CBSEENMA12033054

Solve:
 left parenthesis 1 plus straight y squared right parenthesis thin space left parenthesis 1 plus log space straight x right parenthesis space dx space plus space straight x space dy space equals space 0

Solution

The given differential equation is
                   left parenthesis 1 plus straight y squared right parenthesis thin space left parenthesis 1 plus log space straight x right parenthesis space dx space plus space straight x space dy space equals space 0 space space or space space straight x space dy space equals space minus left parenthesis 1 plus straight y squared right parenthesis thin space left parenthesis 1 plus space log space straight x right parenthesis space dx
Separating the variables, we get,
               fraction numerator dy over denominator 1 plus straight y squared end fraction space equals negative fraction numerator 1 plus log space straight x over denominator straight x end fraction dx
Integrating,   integral fraction numerator 1 over denominator 1 plus straight y squared end fraction dy space equals space minus integral left parenthesis 1 plus log space straight x right parenthesis. space 1 over straight x dx
therefore space space space tan to the power of negative 1 end exponent straight y space plus straight c space equals space minus fraction numerator left parenthesis 1 plus space log space straight x right parenthesis squared over denominator 2 end fraction space space space space space open square brackets because space space integral open square brackets straight f left parenthesis straight x right parenthesis close square brackets to the power of straight n space straight f apostrophe left parenthesis straight x right parenthesis space dx space equals space fraction numerator straight f to the power of straight n plus 1 end exponent left parenthesis straight x right parenthesis over denominator straight n plus 1 end fraction plus straight c close square brackets
therefore space space space tan to the power of negative 1 end exponent straight y space plus space 1 half left parenthesis 1 plus space log space straight x right parenthesis squared space plus space straight c space equals space 0
which is the required solution.