Question

Solve the equation:
a.) 4 cosx=1+2 cosx
I have no idea what to do. Help!!!

Answer 1

I would add -2 cos x to both sides (think of cos x as just another variable)
4 cos x - 2 cos x = 1 + 2 cos x - 2 cos x
the 2 cos x - 2 cos x is 0
4 cos x - 2 cos x is 2 cos x. you get
2 cos x = 1

divide both sides by 2

Answer 2

Sometimes to aid in thinking of cos x as just another variable, as phi suggests, it's easier to just rewrite the equation:
4c = 1 + 2c
2c = 1
c = 1/2
Now put the cos x back in
cos x = 1/2