求cos^3 (3x)的导数?_数学解答

求cos^3 (3x)的导数?

人气：328 ℃　时间：2020-05-10 10:52:39

解答

{cos^3 (3x)}'
= 3 cos^2(3X) {cos(3x)}'
= 3 cos^2(3X) {-sin(3x)} (3x)'
= 3 cos^2(3X) {-sin(3x)} 3
= -9 sin(3x) cos^2(3x)