Question

How do you find all solutions of the equations `cos^3x=cosx` in the interval `[0,2pi)`?

Answer 1

`x = k/2pi, k = 0, +-1, +-2, +-3, ...`.

Explanation:

`cosx (cos^2x-1)=0`, cos x =0 and +-1#

Easily, `x = k/2pi, k = 0, +-1, +-2, +-3, ...`.