JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\left[ \frac{{{e}^{x}}-{{e}^{\sin x}}}{x-\sin x} \right]\]is equal to [UPSEAT 2004]

    A)                 ?1

    B)                 0

    C)                 1

    D)                 None of these

    Correct Answer: C

    Solution :

                       \[\underset{x\to 0}{\mathop{\lim }}\,\left[ \frac{{{e}^{x}}-{{e}^{\sin x}}}{x-\sin x} \right]\],     \[\left( \frac{0}{0}\text{form} \right)\]                    Using L-Hospital?s rule three times, then                    \[\underset{x\to 0}{\mathop{\lim }}\,\frac{{{e}^{x}}-{{e}^{\sin x}}.\cos x}{1-\cos x}=\underset{x\to 0}{\mathop{\lim }}\,\frac{{{e}^{x}}-{{e}^{\sin x}}{{\cos }^{2}}x+\sin x.{{e}^{\sin x}}}{\sin x}\]                    \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{{{e}^{x}}-{{e}^{\sin x}}.{{\cos }^{3}}x+{{e}^{\sin x}}2\cos x\sin x+{{e}^{\sin x}}.\cos x\sin x+{{e}^{\sin x}}.\cos x}{\cos x}\]                                 \[=1\].


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