Anyone know what cos x + 2 cos 2x would simplify to?

Answer 1

It doesn't simplify to anything else. You can write cos(2x) = sin^2(x) - cos^2(x), but that doesn't make the expression simpler, unless you want x to be the argument of every trig function. But there's nothing inherently simpler about it. There's no way to make terms cancel out or top get a single function out of this.

Answer 2

cos x + 2 cos (2x)
= cos x + 2 (2 cos^2 x - 1)
= cos x + 4 cos^2 x - 2

it could only simplify to everything in term of cos x

Answer 3

you can not simplify further..