JEE Main & Advanced JEE Main Paper Phase-I (Held on 09-1-2020 Morning)

  • question_answer
    The integral \[\int{\frac{dx}{{{(x+4)}^{\frac{8}{7}}}{{(x-3)}^{\frac{6}{7}}}}}\] is equal to (where C is a constant of integration) [JEE MAIN Held on 09-01-2020 Morning]

    A) \[\frac{1}{2}\,\,{{\left( \frac{x-3}{x+4} \right)}^{3/7}}+C\]

    B) \[-\frac{1}{13}{{\left( \frac{x-3}{x+4} \right)}^{-13/7}}+C\]

    C) \[{{\left( \frac{x-3}{x+4} \right)}^{1/7}}+C\]

    D) \[-{{\left( \frac{x-3}{x+4} \right)}^{-1/7}}+C\]

    Correct Answer: C

    Solution :

    [c] \[\int{\frac{dx}{{{(x-3)}^{\frac{6}{7}}}{{(x+4)}^{\frac{8}{7}}}}}\]           \[=\int{\frac{dx}{{{\left( \frac{x-3}{x+4} \right)}^{\frac{6}{7}}}.{{(x+4)}^{2}}}}\]   Let \[\frac{x-3}{x+4}=t=1-\frac{7}{x+4}\]  \[=\frac{1}{7}\int{\frac{dt}{{{t}^{\frac{6}{7}}}}}\]                 \[dt=\frac{7}{{{(x+4)}^{2}}}dx\] \[={{t}^{\frac{1}{7}}}+C\] \[={{\left( \frac{x-3}{x+4} \right)}^{\frac{1}{7}}}+C\]


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