اگر $\frac{f(x)}{۲}=x-\left| x \right|$ و $g(x)=۲x+۲|x|$ باشند، مشتق تابع $fog(x)$ کدام است؟
$\begin{align} & (fog)(x)=f(g(x))=2(2x+2\left| x \right|-\left| 2x+2\left| x \right| \right|)=\left\{ \begin{matrix} 0 & x\ge 0 \\ 0 & x\end{matrix} \right. \\ & (fog)(x)=0\Rightarrow (fog{)}'(x)=0 \\ \end{align}$