1. Define a function f as follows: f(x) = x+1 if x 0 x3 +1 if x 0 8 6 4 2 -3 -2 -1 0 1 2 3 The graph of . Use the limit definition of the derivative to show that f is differentiable at x = 0. (b) Show that the derivative function f' is continuous at x = 0, but not differentiable at x = 0.