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

  • question_answer
    \[\int_{{}}^{{}}{x\sqrt{1+{{x}^{2}}}}\ dx=\]                       [MP PET 1989]

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

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

    C)            \[3{{(1+{{x}^{2}})}^{3/2}}+c\]

    D)            \[\frac{1}{3}{{(1+{{x}^{2}})}^{3/2}}+c\]

    Correct Answer: D

    Solution :

                       Put \[1+{{x}^{2}}=t\Rightarrow x\,dx=\frac{dt}{2}\]            It reduces to \[\frac{1}{2}\int_{{}}^{{}}{{{t}^{1/2}}dt}=\frac{1}{2}\times \frac{{{t}^{3/2}}}{3/2}=\frac{1}{3}{{(1+{{x}^{2}})}^{3/2}}+c.\]


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