JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation by Substitution

  • question_answer
    Differential coefficient of \[{{\tan }^{-1}}\left( \frac{x}{1+\sqrt{1-{{x}^{2}}}} \right)\] w.r.t \[{{\sin }^{-1}}x,\] is [Kurukshetra CEE 2002]

    A)            \[\frac{1}{2}\]

    B)            1

    C)            2

    D)            \[\frac{3}{2}\]

    Correct Answer: A

    Solution :

               \[y={{\tan }^{-1}}\left[ \frac{x}{1+\sqrt{1-{{x}^{2}}}} \right]\]            Put \[x=\sin \theta \] Þ \[y={{\tan }^{-1}}\left[ \frac{\sin \theta }{1+\cos \theta } \right]\,=\,{{\tan }^{-1}}\,\tan \frac{\theta }{2}=\frac{\theta }{2}\]            Þ   \[y=\frac{1}{2}{{\sin }^{-1}}x\] and let \[z={{\sin }^{-1}}x\]                    Hence \[\frac{dy}{dz}=\frac{\left( \frac{dy}{dx} \right)}{\left( \frac{dz}{dx} \right)}\]=\[\frac{\frac{1}{2}\frac{d}{dx}{{\sin }^{-1}}x}{\frac{d}{dx}{{\sin }^{-1}}x}\] = \[f''({{e}^{x}}).{{e}^{2x}}+f'({{e}^{x}}).{{e}^{x}}\].


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