Mathematics

Problem

Consider the function

f(x)=\begin{cases}|x+2|,& x< -1\\ x^{2},& -1\le x<2\\ 4-x,& x\ge 2\end{cases}.

At how many points on the real line is

f

not differentiable? a) 2 b) 4 c) 3 d) 5