SOLUTION: question 1 Solve the equation 2 cos2 x + cos x − 1 = 0, 0 ≤ x ≤ 2π.

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Question 645794: question 1
Solve the equation 2 cos2 x + cos x − 1 = 0, 0 ≤ x ≤ 2π.
Answer by lwsshak3(11628) About Me  (Show Source):
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Solve the equation 2 cos2 x + cos x − 1 = 0, 0 ≤ x ≤ 2π.
2cos^2x+cosx-1=0
(2cosx-1)(cosx+1)=0
..
2cosx-1=0
cosx=1/2
x=π/3,5π/3
or
cosx+1=0
cosx=-1
x=π