MCQ
In order that the function $f (x)=(x+1)^{\cot x}$ is continuous at $x=0, f (0)$ must be defined as
  • A
    $f(0)=\frac{1}{e}$
  • B
    $f(0)=0$
  • $f(0)=e$
  • D
    $f(0)=e^2$

Answer

Correct option: C.
$f(0)=e$
(C)
For $f (x)$ to be continuous at $x=0$,
$f (0)=\lim _{x \rightarrow 0} f (x)$
$=\lim _{x \rightarrow 0}(x+1)^{\cot x}$
$=\lim _{x \rightarrow 0}\left\{(1+x)^{\frac{1}{x}}\right\}^{x \cot x}$
$=\lim _{x \rightarrow 0}\left\{(1+x)^{\frac{1}{x}}\right\}^{\lim _{x \rightarrow 0}\left(\frac{x}{\tan x}\right)}$
$= e ^1= e$

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