KVPY Sample Paper KVPY Stream-SX Model Paper-21

  • question_answer
    \[\int{\frac{{{x}^{3}}dx}{\sqrt{1+{{x}^{2}}}}}\] equals:

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

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

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

    D) none of these

    Correct Answer: C

    Solution :

    \[1+{{x}^{2}}={{t}^{2}}\]
    \[\Rightarrow \]\[l=\int{({{t}^{2}}-1)\,dt=\frac{{{t}^{3}}}{3}-t=\frac{{{(1+{{x}^{2}})}^{3/2}}}{3}}-\sqrt{1+{{x}^{2}}}\]\[=\frac{(1+{{x}^{2}})\sqrt{1+{{x}^{2}}}}{3}-\sqrt{1+{{x}^{2}}}\,(1+{{x}^{2}}-{{x}^{2}})\]\[=\frac{1}{3}{{x}^{2}}\sqrt{1+{{x}^{2}}}-\frac{2}{3}{{(1+{{x}^{2}})}^{3/2}}\]


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