JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    The value of \[\underset{x\to 0}{\mathop{\lim }}\,\frac{2}{x}\log (1+x)\] is equal to [Pb. CET 2000]

    A)                 e

    B)                 \[{{e}^{2}}\]

    C)                 \[\frac{1}{2}\]

    D)                 2

    Correct Answer: D

    Solution :

     \[\underset{x\to 0}{\mathop{\lim }}\,\frac{2}{x}\log (1+x)=\underset{x\to 0}{\mathop{\lim }}\,2\log {{(1+x)}^{\frac{1}{x}}}\]                 \[=\underset{x\to 0}{\mathop{\lim }}\,2{{\log }_{e}}e=2\] \[\left\{ \because \underset{x\to 0}{\mathop{\lim }}\,{{(1+x)}^{\frac{1}{x}}}={{\log }_{e}}e=1 \right\}\]                 Trick : Using L Hospital?s rule.


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