Let r(t) = (:2, 1 1', 4t) . Calculate the derivative of r(t) - 30') at: = 8 assuming that 3(8) = (5, _73 7) 3"(8) = (7,9, 3) (Use decimal notation. Give your answer as a whole or exact number.) d _ 582 50'0\") - 3(1)) {=8 Incorrect