Differentiate xcos2x. derivative of xcos2x is =?

We have to
differentiate f(x) = x*cos 2x

f'(x) = x'*cos 2x + x*(cos 2x)'

f'(x) = cos 2x + x*(-sin 2x)*2

f'(x) = cos 2x - 2x*(sin
2x)

The required derivative of f(x) = x*cos 2x is f'(x) = cos
2x - 2x*(sin 2x)