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Vector Algebra

Question
CBSEENMA12033009

Find a one-parameter family of solutions of the following differential equation, indicating carefully the interval in which the solutions are valid:
straight y apostrophe space equals left parenthesis 1 plus straight x squared right parenthesis thin space left parenthesis 1 plus straight y squared right parenthesis






Solution
The given differential equation is
                                          straight y apostrophe space equals left parenthesis 1 plus straight x squared right parenthesis thin space left parenthesis 1 plus straight y squared right parenthesis space space space space or space space space space dy over dx equals left parenthesis 1 plus straight x squared right parenthesis thin space left parenthesis 1 plus straight y squared right parenthesis
Separating the variables, we get,
                fraction numerator 1 over denominator 1 plus straight y squared end fraction dy space equals space left parenthesis 1 plus straight x squared right parenthesis space dx
Integrating,   integral fraction numerator 1 over denominator 1 plus straight y squared end fraction dy space equals space integral left parenthesis 1 plus straight x squared right parenthesis space dx
therefore space space space space space space space tan to the power of negative 1 end exponent straight y space equals space straight x plus straight x cubed over 3 plus straight c comma space space straight x space element of space straight R space is space the space solution. space