MCQ
If $f(x)=\left\{\begin{array}{l}\frac{5}{2}-x, \text { when } x<2 \\ 1, \text { when } x=2 \\ x-\frac{3}{2}, \text { when } x>2\end{array}\right.$, then
  • A
    $f (x)$ is continuous at $x=2$
  • $f (x)$ is discontinuous at $x=2$
  • C
    $\lim _{x \rightarrow 2} f (x)=1$
  • D
    none of these

Answer

Correct option: B.
$f (x)$ is discontinuous at $x=2$
(B)
$\lim _{x \rightarrow 2^{-}} f(x)=\lim _{x \rightarrow 2}\left(\frac{5}{2}-x\right)=\frac{1}{2}$
$\lim _{x \rightarrow 2^{+}} f (x)=\lim _{x \rightarrow 2}\left(x-\frac{3}{2}\right)=\frac{1}{2}$ and $f (2)=1$
$\therefore \quad \lim _{x \rightarrow 2^{-}} f (x)=\lim _{x \rightarrow 2^{+}} f (x) \neq f (2)$
$\therefore f (x)$ is discontinuous at $x=2$.

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