Answer
$(-\infty,2)\cup(2,\infty)$
Work Step by Step
Determine the first derivative $g'(x)$:
$$\begin{align*}
g'(x)=\begin{cases}
2 &&\text{ for }x <0\\
2-2x &&\text{ for }x \in (0,2)\\
-1 &&\text{ for } x >2
\end{cases}
\end{align*}$$
$g'$ does not exist for $x=2$.
