(1 point) Consider f(x) = a(1 - e-bx) for a > 0 and b > 0. Find f' ( x) : f' (x) = Based on your expression for f' (x), is f(x) increasing or decreasing? (Enter increasing or decreasing.) increasing (Be sure that you can see why this is true for all values of x.) Find f" (x) :f"(x) = Based on your expression for f" (x), is f(x) concave up or concave down? (Enter up or down.) down (Be sure that you can see why this is true for all values of x.)