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

  • question_answer
    If \[f(x)=\sqrt{ax}+\frac{{{a}^{2}}}{\sqrt{ax}},\]then \[f'(a)=\]                  [EAMCET 2002]

    A)            ? 1

    B)            1

    C)            0

    D)            a

    Correct Answer: C

    Solution :

               \[f(x)=\sqrt{ax}+\frac{{{a}^{2}}}{\sqrt{ax}},\] then            Þ  \[{f}'(x)=\frac{\sqrt{a}}{2\sqrt{x}}+\frac{{{a}^{2}}}{\sqrt{a}}\left( \frac{-1}{2}{{x}^{-3/2}} \right)\]            Þ  \[{f}'(x)=\frac{\sqrt{a}}{2\sqrt{x}}-\frac{{{a}^{2}}}{2\sqrt{a}}{{x}^{-3/2}}\]            Þ \[{f}'(a)=\frac{\sqrt{a}}{2\sqrt{a}}-\frac{{{a}^{2}}}{2\sqrt{a}\,.\,{{a}^{3/2}}}\]Þ\[{f}'(a)=\frac{1}{2}-\frac{{{a}^{2}}}{2{{a}^{2}}}=0\].


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