JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Integration of Rational Function by Using Partial Fractions

  • question_answer
    \[\int_{{}}^{{}}{\frac{{{x}^{2}}}{({{x}^{2}}+2)({{x}^{2}}+3)}\ }dx=\]        [AISSE 1990]

    A)                 \[-\sqrt{2}{{\tan }^{-1}}x+\sqrt{3}{{\tan }^{-1}}x+c\]

    B)                 \[-\sqrt{2}{{\tan }^{-1}}\frac{x}{\sqrt{2}}+\sqrt{3}{{\tan }^{-1}}\frac{x}{\sqrt{3}}+c\]

    C)                 \[\sqrt{2}{{\tan }^{-1}}\frac{x}{\sqrt{2}}+\sqrt{3}{{\tan }^{-1}}\frac{x}{\sqrt{3}}+c\]

    D)                 None of these

    Correct Answer: B

    Solution :

                       \[\int_{{}}^{{}}{\frac{{{x}^{2}}}{({{x}^{2}}+2)({{x}^{2}}+3)}}\,dx=\int_{{}}^{{}}{\left[ \frac{3}{{{x}^{2}}+3}-\frac{2}{{{x}^{2}}+2} \right]}\,dx\]                                 \[=\frac{3}{\sqrt{3}}{{\tan }^{-1}}\frac{x}{\sqrt{3}}-\frac{2}{\sqrt{2}}{{\tan }^{-1}}\left( \frac{x}{\sqrt{2}} \right)+c\]                                 \[=\sqrt{3}{{\tan }^{-1}}\left( \frac{x}{\sqrt{3}} \right)-\sqrt{2}{{\tan }^{-1}}\left( \frac{x}{\sqrt{2}} \right)+c.\]


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