cos(2x)-3cos(x)-4=0

Solution for cos(2x)-3cos(x)-4=0 equation:

Simplifying
cos(2x) + -3cos(x) + -4 = 0

Remove parenthesis around (2x)
cos * 2x + -3cos(x) + -4 = 0

Reorder the terms for easier multiplication:
2cos * x + -3cos(x) + -4 = 0

Multiply cos * x
2cosx + -3cos(x) + -4 = 0

Multiply cos * x
2cosx + -3cosx + -4 = 0

Reorder the terms:
-4 + 2cosx + -3cosx = 0

Combine like terms: 2cosx + -3cosx = -1cosx
-4 + -1cosx = 0

Solving
-4 + -1cosx = 0

Solving for variable 'c'.

Move all terms containing c to the left, all other terms to the right.

Add '4' to each side of the equation.
-4 + 4 + -1cosx = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -1cosx = 0 + 4
-1cosx = 0 + 4

Combine like terms: 0 + 4 = 4
-1cosx = 4

Divide each side by '-1osx'.
c = -4o-1s-1x-1

Simplifying
c = -4o-1s-1x-1