Below is the graph of a piecewise function f(x). 4 3 2 X 6 -5 4 -3-2-1 1 2 3 4 5 6 2 3 y = f(x) 4 (i (a) lim f(x)= x ->-at 0 3 O 2 O 1 O DNE O - 3 (b) Is f(x) differentiable at x = 4? O true O false