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Find all solutions of the equation in the interval [0, 2π).
6 cos ^2 x + 3 cos x − 3 = 0
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= ---> cancel the factor "3" in both sides. You will get
= ---> Factor both sides. You will get
(2cos(x)-1)*(cos(x) +1) = 0.
The last equation deploys in two independent equations
1. 2cos(x) - 1 = 0 <----> cos(x) = . This equation has two solutions x = and/or x = .
2. cos(x) +1 = 0 <----> cos(x) = -1. This equation has the root x = .
Answer. In the given interval, the original equation has three solutions x = , x = and x = .
