The function $f(x)=\left\{\begin{array}{ll}\frac{2}{5-x}, & x \lt 3 \\ 5-x, & x \geq 3\end{array}\right.$ is

The function $f(x)=\left\{\begin{array}{ll}\frac{2}{5-x}, & x \lt 3 \\ 5-x, & x \geq 3\end{array}\right.$ is
  1. left discontinuous at $x=3$
  2. left continuous at $x=3$
  3. right discontinuous at $x=5$
  4. discontinuous at $x=5$

Solution

Given, $f(x)= \begin{cases}\frac{2}{5-x}, & x \lt 3 \\ 5-x, & x \geq 3\end{cases}$ $\begin{aligned} & \because \lim _{x \rightarrow 3^{-}} f(x)=\lim _{x \rightarrow 3^{-}} \frac{2}{5-x}=\frac{2}{5-3}=1 \\ & \\ & \lim _{x \rightarrow 3^{+}} f(x)=\lim _{x \rightarrow 3^{+}}(5-x)=2 \text { and } f(3)=5-3=2 \end{aligned}$ Since, $\lim _{x \rightarrow 3^{-}} f(x) \neq \lim _{x \rightarrow 3^{+}} f(x)=f(3)$ So, $f(x)$ is left discontinuous at $x=3$.

Asked in: AP EAMCET 2024 (19 May Shift 2)

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