CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2003

  • question_answer
    \[\int{\frac{{{a}^{x/2}}}{\sqrt{{{a}^{-x}}-{{a}^{x}}}}}dx\]is equal to:

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

    B)  \[\frac{1}{\log a}{{\tan }^{-1}}({{a}^{x}})+c\]

    C)  \[2\sqrt{{{a}^{-x}}-{{a}^{x}}}+c\]

    D)  \[\log ({{a}^{x}}-1)+c\]

    E)  \[{{\sin }^{-1}}({{a}^{x}})+c\]

    Correct Answer: A

    Solution :

    Let \[I=\int{\frac{{{a}^{x/2}}}{\sqrt{{{a}^{-x}}-{{a}^{x}}}}}dx\] \[=\int{\frac{{{a}^{x}}}{\sqrt{1-{{a}^{2x}}}}}dx\] Let \[{{a}^{x}}=t\Rightarrow {{a}^{x}}\log a\,dx=dt\] \[\therefore \]  \[I=\int{\frac{dt}{\sqrt{1-{{t}^{2}}}}.\frac{1}{\log a}}\]                 \[=\frac{1}{\log a}{{\sin }^{-1}}(t)+c\]                 \[=\frac{1}{\log a}{{\sin }^{-1}}({{a}^{x}})+c\]    


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