JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation by Substitution

  • question_answer
     If \[y={{a}^{x}}.{{b}^{2x-1}}\], then \[\frac{{{d}^{2}}y}{d{{x}^{2}}}\] is                                  [Kerala (Engg.) 2005]

    A)            \[{{y}^{2}}.\log a{{b}^{2}}\]

    B)            \[y.\log a{{b}^{2}}\]

    C)            \[{{y}^{2}}\]

    D)            \[y.{{(\log {{a}^{2}}b)}^{2}}\]

    E)                 \[y.{{(\log a{{b}^{2}})}^{2}}\]

    Correct Answer: E

    Solution :

               \[y={{a}^{x}}{{b}^{2x-1}}\]                    \[\frac{dy}{dx}={{a}^{x}}{{b}^{2x-1}}\log a+2{{a}^{x}}{{b}^{2x-1}}\log b\]                         = \[{{a}^{x}}{{b}^{2x-1}}(\log a+2\log b)\]                    \[\frac{{{d}^{2}}y}{d{{x}^{2}}}={{a}^{x}}{{b}^{2x-1}}{{(\log a+2\log b)}^{2}}\]                                       \[={{a}^{x}}{{b}^{2x-1}}{{(\log a{{b}^{2}})}^{2}}\]\[=y{{(\log a{{b}^{2}})}^{2}}\].


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