JEE Main & Advanced Mathematics Differentiation Question Bank Derivative at a point Standard Differentiation

  • question_answer
    If \[y={{\tan }^{-1}}\frac{4x}{1+5{{x}^{2}}}+{{\tan }^{-1}}\frac{2+3x}{3-2x}\], then \[\frac{dy}{dx}=\]

    A)            \[\frac{1}{1+25{{x}^{2}}}+\frac{2}{1+{{x}^{2}}}\]

    B)            \[\frac{5}{1+25{{x}^{2}}}+\frac{2}{1+{{x}^{2}}}\]

    C)          \[\frac{5}{1+25{{x}^{2}}}\]

    D)            \[\frac{1}{1+25{{x}^{2}}}\]

    Correct Answer: C

    Solution :

               \[[-3,0]\]                      \[={{\tan }^{-1}}\frac{5x-x}{1+5x.x}+{{\tan }^{-1}}\frac{\frac{2}{3}+x}{1-\frac{2}{3}.x}\]                       \[=6x{{e}^{{{x}^{2}}}}-6x{{e}^{{{x}^{2}}}}+\frac{1}{3}(3)-0=1\]                    Þ \[\frac{dy}{dx}=\frac{5}{1+25{{x}^{2}}}\].


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