JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Integration by Substitution

  • question_answer
    \[\int_{{}}^{{}}{\frac{1}{\log a}({{a}^{x}}\cos {{a}^{x}})dx=}\]

    A)            \[\sin {{a}^{x}}+c\]

    B)            \[{{a}^{x}}\sin {{a}^{x}}+c\]

    C)            \[\frac{1}{{{(\log a)}^{2}}}\sin {{a}^{x}}+c\]

    D)            \[\log \sin {{a}^{x}}+c\]

    Correct Answer: C

    Solution :

                       \[\int_{{}}^{{}}{\frac{1}{\log a}({{a}^{x}}\cos {{a}^{x}})\,dx}\]            Put \[{{a}^{x}}=t\Rightarrow {{a}^{x}}dx=\frac{dt}{\log a},\] then it reduces to            \[\int_{{}}^{{}}{\frac{1}{{{(\log a)}^{2}}}\cos t\,dt}=\frac{1}{{{(\log a)}^{2}}}\sin t+c=\frac{1}{{{(\log a)}^{2}}}\sin {{a}^{x}}+c\].


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