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

  • question_answer
    \[\int_{{}}^{{}}{\frac{dx}{2\sqrt{x}(1+x)}=}\]      [RPET 2002]

    A)            \[\frac{1}{2}{{\tan }^{-1}}(\sqrt{x})+c\]

    B)            \[{{\tan }^{-1}}(\sqrt{x})+c\]

    C)            \[2{{\tan }^{-1}}(\sqrt{x})+c\]

    D)   None of these

    Correct Answer: B

    Solution :

                       \[I=\int{\frac{dx}{2\sqrt{x}(1+x)}}\]. Put \[\sqrt{x}\,=t\]Þ \[\frac{1}{2\sqrt{x}}dx=dt\]            \[\therefore I=\int{\frac{dt}{1+{{t}^{2}}}}={{\tan }^{-1}}t+c\]\[={{\tan }^{-1}}(\sqrt{x})+c\].


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