Find the undefined points given this graph

[angela107]

Homework Statement

Given the following graph, what are the points where the derivative of $y=f(x)$ is undefined?

Relevant Equations

n/a

are the points where the derivative is undefined $x=-4,-2,0, 4$?

 

[member 587159]

No. The derivative in $-4$ exists: there is a horizontal tangent line. In $-2$, $0$ and $4$ the derivatives don't exist.