My Open Math 9 product rule. question 3


for question 3.
f(x)=2x sinx cosx

I am getting
f'(x)= 2x(-sin^2(x)+ cos^2(x))+ (2sin(x)* 2cos(x))

any advice on how to correctly answer the problem?


Well, I’m not sure why you’ve got 2\sin(x) and 2\cos(x) in your last term. I suspect you’ve done something like:

2(\sin(x) \cos(x)) = 2\sin(x) 2\cos(x)

But that’s not correct.