(frac{d}{dx}) cos(3x(^2) – 2x) is equal to

A.
sin(6x – 2) 
B.
sin(3x^{2} – 2x)dx 
C.
(6x – 2) sin(3x^{2} – 2x) 
D.
(6x – 2)sin(3x^{2} – 2x)
Correct Answer: Option D
Explanation
Let (3x^{2} – 2x = u)
(y = cos u implies frac{mathrm d y}{mathrm d u} = – sin u)
(frac{mathrm d u}{mathrm d x} = 6x – 2)
(therefore frac{mathrm d y}{mathrm d x} = (6x – 2) . – sin u)
= ( (6x – 2) sin (3x^{2} – 2x))