JEE Main & Advanced Mathematics Differentiation Question Bank Partial Differentiation

  • question_answer
    If \[{{x}^{x}}{{y}^{y}}{{z}^{z}}=c\], then \[\frac{\partial z}{\partial x}=\]                                  [EAMCET 1999]

    A)            \[\frac{1+\log x}{1+\log z}\]

    B)            \[-\frac{1+\log x}{1+\log z}\]

    C)            \[-\frac{1+\log y}{1+\log z}\]

    D)            None of these

    Correct Answer: B

    Solution :

                       \[{{x}^{x}}{{y}^{y}}{{z}^{z}}=c\]Þ \[\log ({{x}^{x}}{{y}^{y}}{{z}^{z}})=\log c\]                    Þ \[x\log x+y\log y+z\log z=\log c\]                    .....(i)                    Here x, y are regarded as independent variables and z depends on x, y.                    Differentiating (i) partially w.r.t. ?x?                    \[x.\frac{1}{x}+\log x.1+0+\left( z.\frac{1}{z}+\log z.1 \right)\frac{\partial z}{\partial x}=0\]                    \[\therefore \] \[\frac{\partial z}{\partial x}=-\frac{1+\log x}{1+\log z}\].


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