15. A function f(x) that satisfies the equation f(x). f'(x) =x and f(0) =1 is (A) f ( x) = ex (B) f ( x) = x (C) f(x) = Vx2+1 (D) f( x) = V1-x2 16. At each point (x, y) on a certain curve, the slope of the curve is y If the curve contains the point (0, 8), 2V x then its equation is (A) In y = 8Vx-2 (B) y = 8 x (C) y = 8e VX-2 (D) Iny = 4Vx - 8