Question:
Let $f(x)=\left\{\begin{array}{l}\frac{x}{|x|^{\prime}} x \neq 0 \\ 0, x=0\end{array}\right.$
Show that $\lim _{x \rightarrow 0} f(x)$ does not exist.
Solution:
Left Hand Limit(L.H.L.):
$\lim _{x \rightarrow 0^{-}} f(x)=\lim _{x \rightarrow 0^{-}} \frac{x}{|x|}$
$=\lim _{x \rightarrow 0^{-}} \frac{x}{(-x)}$
$=\lim _{x \rightarrow 0^{-}}-1$
$=-1$
Right Hand Limit(R.H.L.):
$\lim _{x \rightarrow 0^{+}} f(x)=\lim _{x \rightarrow 0^{+}} \frac{x}{|x|}$
$=\lim _{x \rightarrow 0^{+}} \frac{x}{(+x)}$
$=\lim _{x \rightarrow 0^{+}} 1$
$=1$
Since $\lim _{x \rightarrow 0^{-}} f(x) \neq \lim _{x \rightarrow 0^{+}} f(x), \lim _{x \rightarrow 0} f(x)$ does not exist