JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{n\to \infty }{\mathop{\lim }}\,\frac{1}{2}+\frac{1}{{{2}^{2}}}+\frac{1}{{{2}^{3}}}+...+\frac{1}{{{2}^{n}}}\]equals [RPET 1996]

    A)                 2

    B)                 ?1

    C)                 1

    D)                 3

    Correct Answer: C

    Solution :

                       \[y=\underset{n\to \infty }{\mathop{\lim }}\,\,\frac{1}{2}+\frac{1}{{{2}^{2}}}+\frac{1}{{{2}^{3}}}+.......+\frac{1}{{{2}^{n}}}=\underset{n\to \infty }{\mathop{\lim }}\,\,\,\frac{1}{2}\,\frac{\left[ 1-{{\left( \frac{1}{2} \right)}^{n}} \right]}{\left( 1-\frac{1}{2} \right)}\]                 \[\underset{n\to \infty }{\mathop{\lim }}\,\,\left[ 1-\frac{1}{{{2}^{n}}} \right]=1-0=1\]


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