Answer:
dy/dx = 6x(x²-3)cos2x - 2(x²-3)³sin2x
Explanation:
We use the Product Rule:
y= (x²-3)³cos2x
dy/dx = (x²-3)³ d(cos2x)/dx + cos2x * d ((x²-3)³)/dx
= (x²-3)³ * -2sin2x + cos2x * 3(x²-3)*2x
= -2sin2x*(x²-3)³ + 6xcos2x*(x²-3)
= 6x(x²-3)cos2x - 2(x²-3)³sin2x