Question

Verify the identity.

cos 4x + cos 2x = 2 - 2 sin^2 2x - 2 sin^2 x

Answer 1

is that cos4x or cos^4(x) and is it cos2x or cos^2(x)

@JoshKPatterson

Answer 2

cos 4x + cos 2x. No exponents on them.

Answer 3

@genius12

Answer 4

\[\cos 4x+\cos 2x=\cos (2x+2x)+\cos 2x=\cos 2x \cos 2x-\sin 2x \sin 2x+\cos 2x\]

Answer 5

\[(2\cos ^2-1)(1-2\sin ^2)-2\sin x \cos x2\sin x \cos x+2\cos ^2x-1\]

Answer 6

\[2\cos ^2x-4\sin^2x \cos ^2x-1+2\sin ^2x-4\sin ^2x \cos ^2x+2\cos ^2x-1\]

Answer 7

\[4\cos ^2x-8\sin ^2x \cos ^2x+2\sin ^2x-2\]