JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[[.]\]is equal to               [IIT 1984; DCE 2000; Pb. CET 2000]

    A)                 0

    B)                 \[-\frac{1}{2}\]

    C)                 \[\log \left( \frac{2}{3} \right)\]

    D)                 None of these

    Correct Answer: B

    Solution :

                       \[\underset{n\to \infty }{\mathop{\lim }}\,\,\left[ \frac{1}{1-{{n}^{2}}}+\frac{2}{1-{{n}^{2}}}+.....+\frac{n}{1-{{n}^{2}}} \right]\]                                 \[=\underset{n\to \infty }{\mathop{\lim }}\,\,\frac{\Sigma n}{1-{{n}^{2}}}=\frac{1}{2}\,\,\underset{n\to \infty }{\mathop{\lim }}\,\,\,\,\frac{{{n}^{2}}+n}{1-{{n}^{2}}}=-\frac{1}{2}\].


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