SOLUTION: solve for (0,2pi) 4cos x+ 4cos^2 x+1=0

Question 1075178: solve for (0,2pi)
4cos x+ 4cos^2 x+1=0

Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
4cos x+ 4cos^2 x+1=0
4cos^2 + 4cos + 1 = 0
(2cos + 1)^2 = 0
cos(x) = -1/2
x = 5pi/6, 7pi/6
Answer by ikleyn(52856) (Show Source): You can put this solution on YOUR website!
.
4cos x+ 4cos^2 x+1=0

4cos^2 + 4cos + 1 = 0

(2cos + 1)^2 = 0

cos(x) = -1/2

x = 2pi/3, 4pi/3

The solution by other tutor is incorrect.

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