1. Define a function f as follows: f (x) = x2 +1 ifx0 00 4 2 -3 -2 -1 0 2 The graph of f. (a) 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