Question

HELP NEEDED: see attachment

Answer 1

attachment

Answer 2

cos2x=cosx
2x=x
0=x

Answer 3

medal please

Answer 4

I would start like this:

\[\cos(2x)=\cos^2x-\sin^2x = \cos^2x-(1-\cos^2x)=2\cos^2x-1\]
so you will get the quadratic equation after back substitution:
\[2\cos^2x-cosx-1=0\]

Answer 5

much thanks to ivan514 and spacelimbus

Answer 6

wtf spacelimbs

Answer 7

what's wrong with it?

Answer 8

so much work

Answer 9

true that (x