MCQ
$\mathop {\lim }\limits_{x \to 1} f(x)$ is equal to, where

$f(x) = \left\{ {\begin{array}{*{20}{c}}
{\frac{{{e^{\frac{1}{{x - 1}}}} - 2}}{{{e^{\frac{1}{{x - 1}}}} + 2}}}&{x \ne 1}\\
{1\,\,\,\,\,\,\,\,\,\,\,\,\,}&{x = 1}
\end{array}} \right.$

  • A
    $-1$
  • B
    $1$
  • C
    $0$
  • does not exist

Answer

Correct option: D.
does not exist
d
$L.H.L$ $ = \mathop {\lim }\limits_{x \to {1^ - }} \frac{{{e^{\frac{1}{{x - 1}}}} - 2}}{{{e^{\frac{1}{{x - 1}}}} + 2}} = \mathop {\lim }\limits_{h \to {0^ - }} \frac{{{e^{ - \frac{1}{h}}} - 2}}{{{e^{ - \frac{1}{h}}} + 2}} =  - 1$

$R.H.L$ $ = \mathop {\lim }\limits_{x \to {1^ - }} \frac{{{e^{\frac{1}{{x - 1}}}} - 2}}{{{e^{\frac{1}{{x - 1}}}} + 2}} = \mathop {\lim }\limits_{h \to {0^ + }} \frac{{{e^{\frac{1}{h}}} - 2}}{{{e^{\frac{1}{h}}} + 2}}$

$ = \mathop {\lim }\limits_{h \to {0^ + }} \frac{{1 - 2{e^{\frac{1}{h}}}}}{{1 + 2{e^{ - \frac{1}{h}}}}} = 1$

as $\mathrm{L} . \mathrm{H} . \mathrm{L} \neq \mathrm{R} . \mathrm{H} . \mathrm{L}.$

limit does not exist.

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