JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Self Evaluation Test - Integrals

  • question_answer
    If\[f(x)=ln(x-\sqrt{1+{{x}^{2}}})\], then what is \[\int{f''(x)dx}\] equal to?

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

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

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

    D) \[\text{ln}\,(x-\sqrt{1+{{x}^{2}}})+c\]

    Correct Answer: B

    Solution :

    [b] Given that \[f(x)=ln\,\,(x-\sqrt{1+{{x}^{2}}})\] \[\int{f''(x)dx=f'(x)+c}\] where c is a constant \[=\frac{1}{(x-\sqrt{1+{{x}^{2}}})}.\left( 1-\frac{2x}{2\sqrt{1+{{x}^{2}}}} \right)+c\] \[=\frac{-(x-\sqrt{1+{{x}^{2}}})}{(\sqrt{1+{{x}^{2}}})(x-\sqrt{1+{{x}^{2}}})}+c=-\frac{1}{\sqrt{1+{{x}^{2}}}}+c\]


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