JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\left[ \frac{1}{x}-\frac{\log (1+x)}{{{x}^{2}}} \right]\]=

    A)                 ½

    B)                 ?1/2

    C)                 1

    D)                 ?1

    Correct Answer: A

    Solution :

                       Expand \[\log \,(1+x)\] and then solve.            Aliter : Apply L-Hospital?s rule, \[\underset{x\to 0}{\mathop{\lim }}\,\,\left[ \frac{x-\log \,(1+x)}{{{x}^{2}}} \right]\]                                 \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{1-\frac{1}{1+x}}{2x}\]\[=\underset{x\to 0}{\mathop{\lim }}\,\,\,\frac{1}{2}\,{{\left( \frac{1}{1+x} \right)}^{2}}=\frac{1}{2}.\]


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