JEE Main & Advanced Mathematics Differentiation Question Bank Self Evaluation Test - Limits and Derivatives

  • question_answer
    If \[f(x)=\frac{\sin ({{e}^{x-2}}-1)}{in(x-1)},\] then \[\underset{x\to 2}{\mathop{\lim }}\,f(x)\] is equal to

    A) \[-2\]

    B) \[-1\]

    C) \[0\]

    D) 1

    Correct Answer: D

    Solution :

    [d] \[f(x)=\frac{\sin \left( {{e}^{x-2}}-1 \right)}{In(x-1)}\]
    \[\underset{x\to 2}{\mathop{\lim }}\,\frac{\sin \left( {{e}^{x-2}}-1 \right)}{In(x-1)}=L\]
    It is \[\frac{0}{0}\](undefined) condition so using Hospital?s rule
    \[\Rightarrow L=\underset{x\to 2}{\mathop{\lim }}\,\left[ \frac{\{sin\left( {{e}^{x-2}}-1 \right)\}}{\{In(x-1)\}} \right]\]
    \[\Rightarrow L=\underset{x\to 2}{\mathop{\lim }}\,\frac{\cos ({{e}^{x-2}}-1).{{e}^{(x-2)}}}{1/(x-1)}\]
    \[\Rightarrow L=\underset{x\to 2}{\mathop{\lim }}\,\cos \left( {{e}^{2-2}}-1 \right){{e}^{2-2}}.(2-1)\]
    \[\Rightarrow L=\cos (0){{e}^{0}}.1\Rightarrow L=1\]


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