- If $\displaystyle{\lim_{x \to a^+} f(x)}$ and $\displaystyle{
\lim_{x \to a^-} f(x)}$ both exist, but are different, then we have
a jump discontinuity. (Below $a=-1$.)
-
If either $\displaystyle{\lim_{x \to a^+} f(x)} = \pm \infty$
or $\displaystyle{\lim_{x \to a^-} f(x)} = \pm \infty$, then we have an
infinite discontinuity, also called an asymptotic discontinuity. (Below $a=-1$.)
-
If $\displaystyle{\lim_{x \to a^+} f(x)}$ and
$\displaystyle{\lim_{x \to a^-} f(x)}$ exist and are equal (and finite), but
$f(a)$ happens to be different (or doesn't exist), then we have a
removable discontinuity, since by changing the value of $f(x)$ at
a single point we can make $f(x)$ continuous. (Below $a=1$.)
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