Factor the trigonometric equation. cos2x-cosx

Cos(2x) = cos^2(x) - sin^2(x) - cos(x)

but sin^2(x) = 1 - cos^2(x)

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

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

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

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

I think this is what you have asked for.