SOLUTION: Find the solutions of the equation cos 2x + cos 𝑥 + 1 = 0 in the interval [0, 2𝜋). Check your answer if it is a solution or not.

Question 1182984: Find the solutions of the equation cos 2x + cos 𝑥 + 1 = 0 in the interval [0, 2𝜋). Check your answer if it is a solution or not.
Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
cos2x + cosx + 1 = cos^2x - sin^2x + cosx + cos^2 x + sin^2x = 2cos^2x + cosx = 0
==> cosx(2cosx + 1) = 0 ==> cos x = 0 or 2cosx + 1 = 0
cosx = 0 ==> x = or

2cosx + 1 = 0 ==> x = or
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