f(x)={−1,x2−1,−2≤x<00≤x≤2 $\text { Then, } f(x \mid)=\left{\begin{array}{cc}
-1, & -2 \leq|x| < 0 \
|x|^{2}-1, & 0 \leq|x| \leq 2
\end{array}\right.\Rightarrow f(|x|)=x^{2}-1,-2 \leq x \leq 2\Rightarrow g(x)=\left{\begin{aligned} 1+x^{2}-1, &-2 \leq x < 0 \\left(x^{2}-1\right)+\left|x^{2}-1\right|, & 0 \leq x \leq 2 \end{aligned}\right.=\left{\begin{array}{cc}x^{2}, & -2 \leq x < 0 \ 0, & 0 \leq x < 1 \ 2\left(x^{2}-1\right), & 1 \leq x \leq 2\end{array}\right.g^{\prime}\left(0^{-}\right)=0, g^{\prime}\left(0^{*}\right)=0, g^{\prime}\left(1^{-}\right)=0, g^{\prime}\left(1^{+}\right)=4\Rightarrow g(x)isnon−differentiableatx=1\Rightarrow g(x)$ is not differentiable at one point.