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

  • question_answer
    \[\int_{{}}^{{}}{\frac{2x{{\tan }^{-1}}{{x}^{2}}}{1+{{x}^{4}}}}\ dx=\] [Roorkee 1982]

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

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

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

    D)            None of these

    Correct Answer: B

    Solution :

                       Put \[t={{\tan }^{-1}}{{x}^{2}}\Rightarrow dt=\frac{1}{1+{{x}^{4}}}\,2x\,dx,\] then            \[\int_{{}}^{{}}{\frac{2x{{\tan }^{-1}}{{x}^{2}}}{1+{{x}^{4}}}}\,dx=\int_{{}}^{{}}{t\,dt}=\frac{{{t}^{2}}}{2}+c=\frac{1}{2}{{({{\tan }^{-1}}{{x}^{2}})}^{2}}+c.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner