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

  • question_answer
    \[\int_{{}}^{{}}{{{\tan }^{-1}}x\,dx=}\]    [Roorkee 1977]

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

    B)                 \[x{{\tan }^{-1}}x-\frac{1}{2}\log (1+{{x}^{2}})\]

    C)                 \[(x-1){{\tan }^{-1}}x\]

    D)                 \[x{{\tan }^{-1}}x-\log (1+{{x}^{2}})\]

    Correct Answer: B

    Solution :

                    \[\int_{{}}^{{}}{{{\tan }^{-1}}x\,dx}=x{{\tan }^{-1}}x-\int_{{}}^{{}}{\frac{x}{1+{{x}^{2}}}\,dx+c}\]                                         \[=x{{\tan }^{-1}}x-\frac{1}{2}\log (1+{{x}^{2}})+c.\]                 Note : Students should remember this question as a formula.


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