JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to \infty }{\mathop{\lim }}\,[x({{a}^{1/x}}-1)]\],\[(a>1)=\]

    A)                 \[\log x\]

    B)                 1

    C)                 0

    D)                 \[-\log \frac{1}{a}\]

    Correct Answer: D

    Solution :

                       \[\underset{x\to \infty }{\mathop{\lim }}\,x\,({{a}^{1/x}}-1)=\underset{x\to \infty }{\mathop{\lim }}\,\,\left[ \frac{{{a}^{1/x}}-1}{1/x} \right]\]                                           \[=\underset{x\to \infty }{\mathop{\lim }}\,\frac{[{{e}^{{{\log }_{e}}{{a}^{1/x}}}}-1]}{1/x}={{\log }_{e}}a=-{{\log }_{e}}\frac{1}{a}.\]


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