JEE Main & Advanced Mathematics Functions Question Bank Limits

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

    A)                 ?2

    B)                 ?1

    C)                 0

    D)                 1

    Correct Answer: D

    Solution :

                       \[\underset{x\to 2}{\mathop{\lim }}\,\,\,f(x)=\underset{x\to 2}{\mathop{\lim }}\,\,\frac{\sin \,({{e}^{x-2}}-1)}{\log \,(x-1)}\]            \[=\underset{t\to 0}{\mathop{\lim }}\,\,\,\frac{\sin \,({{e}^{t}}-1)}{\log \,(1+t)}\], {Putting \[x=2+t\}\]            \[=\underset{t\to 0}{\mathop{\lim }}\,\,\,\frac{\sin \,({{e}^{t}}-1)}{{{e}^{t}}-1}.\frac{{{e}^{t}}-1}{t}.\frac{t}{\log \,(1+t)}\]            \[=\underset{t\to 0}{\mathop{\lim }}\,\,\,\frac{\sin \,({{e}^{t}}-1)}{{{e}^{t}}-1}.\left( \frac{1}{1\,\,!}+\frac{t}{2\,\,!}+... \right)\times \left[ \frac{1}{\left( 1-\frac{1}{2}t+\frac{1}{3}{{t}^{2}}-... \right)} \right]\]                                 \[=1\,\,.\,\,1\,\,.\,\,1=1,\,\,\,\,(\because \,\,\text{As}\,\,t\to 0,\,\,{{e}^{t}}-1\to 0).\]


You need to login to perform this action.
You will be redirected in 3 sec spinner