JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Self Evaluation Test - Integrals

  • question_answer
    \[\int{\frac{(1+x){{e}^{x}}}{\cot (x{{e}^{x}})}dx}\] is equal to

    A) \[\log \left| \cos (x{{e}^{x}}) \right|+C\]

    B) \[\log \left| \cot (x{{e}^{x}}) \right|+C\]

    C) \[\log \left| sec(x{{e}^{-x}}) \right|+C\]

    D) \[\log \left| sec(x{{e}^{x}}) \right|+C\]

    Correct Answer: D

    Solution :

    [d] Let \[I=\int{\frac{(1+x){{e}^{x}}}{\cot (x{{e}^{x}})}}dx\] Put \[x{{e}^{x}}=t\Rightarrow (x{{e}^{x}}+{{e}^{x}})dx=dt\] \[\Rightarrow {{e}^{x}}(x+1)dx=dt\] \[\therefore \,\,\,\,\,I=\int{\frac{dt}{\cot (t)}=\log \left| \sec t \right|+C}\] \[=\log \left| \sec (x{{e}^{x}}) \right|+C\]


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