Consider the graph. (Enter your answers as comma-separated lists. If an answer does not exist, enter DNE.) WebAssign Plot X - 4 -2 -1 1 2 3 4 -1 -2 -3 (a) Determine for which values of x = a the lim f(x) exists but f is not continuous at x = a. X-a X = (b) Determine for which values of x = a the function is continuous but not differentiable at x = a. X =