MCQ
Consider the function $f:(0, \infty) \rightarrow R$ defined by $f(x)=e^{-\left|\log _e x\right|}$. If $m$ and $n$ be respectively the number of points at which $f$ is not continuous and $f$ is not differentiable, then $\mathrm{m}+\mathrm{n}$ is
  • A
    $0$
  • B
    $3$
  • $1$
  • D
    $2$

Answer

Correct option: C.
$1$
c
$f:(0, \infty) \rightarrow R$

$ f(x)=e^{-\left|\log _e x\right|}$

$\mathrm{f}(\mathrm{x})=\frac{1}{\mathrm{e}^{\ln x \mid}}=\left\{\begin{array}{l}\frac{1}{\mathrm{e}^{-\ln x}} ; 0 < \mathrm{x} < 1 \\ \frac{1}{\mathrm{e}^{\ln x}} ; \mathrm{x} \geq 1\end{array}\right.$

$\left\{\begin{array}{l}\frac{1}{\frac{1}{x}}=x ; 0 < x < 1 \\ \frac{1}{x}, x \geq 1\end{array}\right.$

${m}=0$ (No point at which function is not continuous)

{n}=$1$ (Not differentiable)

$\therefore \mathrm{m}+\mathrm{n}=1$

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