JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation by Substitution

  • question_answer
    If \[y={{\sin }^{-1}}\frac{2x}{1+{{x}^{2}}}+{{\sec }^{-1}}\frac{1+{{x}^{2}}}{1-{{x}^{2}}}\], then \[\frac{dy}{dx}\]=            [RPET 1996]

    A)            \[\frac{4}{1-{{x}^{2}}}\]

    B)            \[\frac{1}{1+{{x}^{2}}}\]

    C)            \[\frac{4}{1-{{x}^{2}}}\]

    D)            \[\frac{-4}{1+{{x}^{2}}}\]

    Correct Answer: C

    Solution :

               Putting \[x=\tan \theta \]                    \[y={{\sin }^{-1}}\left( \frac{2\tan \theta }{1+{{\tan }^{2}}\theta } \right)+{{\sec }^{-1}}\left( \frac{1+{{\tan }^{2}}\theta }{1-{{\tan }^{2}}\theta } \right)\]              \[=2\theta +2\theta =4{{\tan }^{-1}}x\].            \[y={{\sin }^{-1}}\left( \frac{2\tan \theta }{1+{{\tan }^{2}}\theta } \right)+{{\sec }^{-1}}\left( \frac{1+{{\tan }^{2}}\theta }{1-{{\tan }^{2}}\theta } \right)\]            Þ  \[x=0\].


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