Question

List all the numbers x at which the function graphed above is not differentiable. Separate answers using commas.

Answer 1

At x=-2 the function does not exists, it means that at this x value, the function is not differentiable.

At x=1 the function has a peak, it means that at this x value, the function is not differentiable.

It means that the answer is: -2, 1.