Question 312174: Please help me with this question and show all steps if possible thank you! Found 2 solutions by fractalier, Fombitz:Answer by fractalier(6550) (Show Source):
You can put this solution on YOUR website! Okay from
3 cos2x = cosx +2
let's apply our identity for cos 2x...
cos 2x = cos^2 x - sin^2 x = 2 cos^2 x - 1
so that if we substitute we get
3(2 cos^2 x - 1) = cos x + 2
6 cos^2 x - 3 = cos x + 2
6 cos^2 x - cos x - 5 = 0 now factor this...
(6 cos x + 5)(cos x - 1) = 0
and then
cos x = -5/6 or cos x = 1
x = arc cos (-5/6) or x = 0
