18.A particle’s position is given by s = t^3 − 6t^2 + 9t. What is its acceleration at time t = 4 ?
(A) 0
(B) −9
(C) −12
(D) 1219.If f(x) = 3πx, then f′(x) =
(A)
(B)
(C) π(3πx − 1)(D) π ln 3(3πx)20.The average value of f(x) = from x = 1 to x = e is
(A)
(B)
(C) e − 1(D)
21.If f(x) = sin^2 x, find f′′′(x).
(A)−sin^2 x
(B)cos 2x
(C)−4 sin 2x
(D)−sin 2x22.Find the slope of the normal line to y = x + cos xy at (0, 1).