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

  • question_answer
    \[\frac{d}{dx}\left[ \log \left\{ {{e}^{x}}{{\left( \frac{x+2}{x-2} \right)}^{3/4}} \right\} \right]\] equals                              

    A)            \[\frac{{{x}^{2}}-7}{{{x}^{2}}-4}\]

    B)            1

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

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

    Correct Answer: A

    Solution :

               \[y=\log {{e}^{x}}+\frac{3}{4}\log \frac{x+2}{x-2}=x+\frac{3}{4}\log \frac{x+2}{x-2}\]                    Þ  \[y=x+\frac{3}{4}\left[ \log (x+2)-\log (x-2) \right]\] \[\frac{dy}{dx}=1+\frac{3}{4}\left[ \frac{1}{x+2}-\frac{1}{x-2} \right]=1-\frac{3}{{{x}^{2}}-4}\] \[\frac{dy}{dx}=\frac{{{x}^{2}}-7}{{{x}^{2}}-4}\].


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