JEE Main & Advanced Mathematics Definite Integration Question Bank Fundamental definite integration, Definite integration by substitution

  • question_answer
    \[\int_{0}^{1}{\frac{{{\tan }^{-1}}x}{1+{{x}^{2}}}}\,dx=\]             [SCRA 1987; MNR 1990]

    A)                 \[\frac{{{\pi }^{2}}}{8}\]

    B)                 \[\frac{{{\pi }^{2}}}{16}\]

    C)                 \[\frac{{{\pi }^{2}}}{4}\]

    D)                 \[\frac{{{\pi }^{2}}}{32}\]

    Correct Answer: D

    Solution :

               Put \[t={{\tan }^{-1}}x\Rightarrow dt=\frac{1}{1+{{x}^{2}}}dx,\] then                                 \[\int_{0}^{1}{\frac{{{\tan }^{-1}}x}{1+{{x}^{2}}}dx=\int_{0}^{\pi /4}{t\,dt=\left[ \frac{{{t}^{2}}}{2} \right]_{0}^{\pi /4}=\frac{{{\pi }^{2}}}{32}}}\].


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