JEE Main & Advanced Sample Paper JEE Main Sample Paper-18

  • question_answer
    The value of the limit,\[\underset{n\to \infty }{\mathop{\lim }}\,\int\limits_{0}^{1}{\frac{n\cdot {{x}^{n-1}}}{1+x}}\,dx\]equals

    A)  1/2                       

    B)  0

    C)  1                            

    D)  2

    Correct Answer: A

    Solution :

     \[\underset{n\to \infty }{\mathop{\text{Lim}}}\,\int\limits_{{}}^{1}{\,\frac{n\cdot {{x}^{n-1}}}{1+x}}\,dx\] \[=\underset{n\to \infty }{\mathop{\lim }}\,\left[ \int\limits_{0}^{1}{\frac{1}{\underbrace{1+x}_{\text{I}}}\cdot \underbrace{n\cdot {{x}^{n-1}}}_{\text{II}}dx} \right]\] \[=\left. \frac{1}{1+x}\cdot {{x}^{n}} \right|_{0}^{1}+\int\limits_{0}^{1}{\,\frac{{{x}^{n}}}{{{(1+x)}^{2}}}dx}\] \[=\frac{1}{2}+0\] (as\[n\to \infty \])


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