Definition: Suppose $f(x)$ is
defined for all $x$ in an interval about $a$ (possibly excluding $a$).
$$ \lim_{x
\rightarrow a} f(x) = \ell$$
(read: "the limit of $f(x)$, as $x$ approaches $a$,
equals $\ell$") means that we can get $f(x)$ as close to
$\ell$ as we want by making $x$ sufficiently
close to $a$. |