JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Critical Thinking

  • question_answer
    \[\int_{{}}^{{}}{\frac{{{x}^{3}}-x-2}{(1-{{x}^{2}})}\ dx=}\]    [AI CBSE 1985]

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

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

    C) \[\log \left( \frac{x+1}{x-1} \right)+\frac{{{x}^{2}}}{2}+c\]

    D) \[\log \left( \frac{x-1}{x+1} \right)-\frac{{{x}^{2}}}{2}+c\]

    Correct Answer: D

    Solution :

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


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