4. let f(x) = ⎧ ⎨ ⎩ 0 if x < 0 x if 0 ≤ x ≤ 1 2 − x if 1 < x ≤ 2 0 ifx > 2 and g(x) = ∫ x 0 f(t) dt (a) find an expression for g(x) similar to the one for f(x). (b) sketch the graphs of f and g. (c) where is f differentiable? where is g differentiable?