JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    For \[x\in R,\,\,\,\underset{x\to \infty }{\mathop{\lim }}\,\,{{\left( \frac{x-3}{x+2} \right)}^{x}}\] is equal to [IIT Screening 2000]

    A)                 e

    B)                 \[{{e}^{-1}}\]

    C)                 \[{{e}^{-5}}\]

    D)                 \[{{e}^{5}}\]

    Correct Answer: C

    Solution :

                       \[\underset{x\to \infty }{\mathop{\lim }}\,{{\left( \frac{x+2-5}{x+2} \right)}^{x}}=\underset{x\to \infty }{\mathop{\lim }}\,{{\left[ {{\left( 1-\frac{5}{x+2} \right)}^{\frac{x+2}{-5}}} \right]}^{-\,\frac{5x}{x+2}}}={{e}^{-5}}\]                                                                  \[\left( \because \,\underset{x\to \infty }{\mathop{\lim }}\,\frac{-5x}{x+2}=\,\underset{x\to \infty }{\mathop{\lim }}\,\frac{-5}{1+\frac{2}{x}}=-5 \right)\].


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