JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation of implicit function Parametric

  • question_answer
    If \[{{x}^{y}}={{y}^{x}},\]then \[\frac{dy}{dx}=\]                       [DSSE 1996; MP PET 1997]

    A)            \[\frac{y(x{{\log }_{e}}y+y)}{x(y{{\log }_{e}}x+x)}\]

    B)            \[\frac{y(x{{\log }_{e}}y-y)}{x(y{{\log }_{e}}x-x)}\]

    C)            \[\frac{x(x{{\log }_{e}}y-y)}{y(y{{\log }_{e}}x-x)}\]

    D)            \[\frac{x(x{{\log }_{e}}y+y)}{y(y{{\log }_{e}}x+x)}\]

    Correct Answer: B

    Solution :

               \[{{x}^{y}}={{y}^{x}}\Rightarrow y{{\log }_{e}}x=x{{\log }_{e}}y\]            Differentiating w.r.t. x of y, we get            \[{{\log }_{e}}x\frac{dy}{dx}+\frac{y}{x}={{\log }_{e}}y+x\frac{1}{y}\frac{dy}{dx}\]                    \[\therefore \frac{dy}{dx}=\frac{y(x{{\log }_{e}}y-y)}{x(y{{\log }_{e}}x-x)}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner