JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{n\to \infty }{\mathop{\lim }}\,\,{{\left( \frac{{{n}^{2}}-n+1}{{{n}^{2}}-n-1} \right)}^{n(n-1)}}=\] [AMU 2002]

    A)                 e

    B)                 \[{{e}^{2}}\]

    C)                 \[{{e}^{-1}}\]

    D)                 1

    Correct Answer: B

    Solution :

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


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