Ответ:

12cos^3(3x) × (-sin(3x))

Объяснение:

f (x) = cos^4(3x)

f ` (x) = (cos^4(3x)) ` = 4cos^3(3x) × (cos(3x)) ` = 4cos^3(3x) × (-sin(3x)) × (3x) ` = 4cos^3(3x) × (-sin(3x)) × 3 = 12cos^3(3x) × (-sin(3x))