Question
Identify discontinuities for the following functions as either a jump or a removable discontinuity :
$f(x)=x^2-3 x-2$, for $x<-3=3+8 x$, for $x>-3$.

Answer

$f(x)=x^2-3 x-2, x<-3=3+8 x, x>-3$
$f(x)$ is a polynomial function for both the intervals.
$\therefore f ( x )$ is continuous for both the given intervals.
Let us test the continuity at $x =-3$.
$\lim _{x \rightarrow-3^{-}} f (x)=\lim _{x \rightarrow-3^{-}}\left(x^2-3 x-2\right)$
$=(-3)^2-3(-3)-2$
$=9+9-2$
$=16$
$\lim _{x \rightarrow-3^{+}} f(x)=\lim _{x \rightarrow-3^{+}}(3+8 x)$
$=3+8(-3)$
$=-21$
$\therefore \quad \lim _{x \rightarrow-3^{-}} f (x) \neq \lim _{x \rightarrow-3^{+}} f (x)$
$\therefore \quad \lim _{x \rightarrow-3} f (x) \text { does not exist. }$
$\therefore f ( x )$ is discontinuous at $x =-3$.
$\therefore f ( x )$ has a jump discontinuity at $x =-3$

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