math
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Solve 3sin2x  1 = 0
Interval: [0, 2 pi]
Solve 6cos^2x + 5cosx  6 = 0

For the first one, sin2x = 1/3
2x = 0.33984, 2.80176 or 6.62302 radians (and one more less than 4 pi)
x = 0.16992, 1.4088, or 3.3115
(and one more less than 2 pi that I will leave you to figure out)
For the second question, factor into
(2cosx +3)(3cosx 2) = 0
Then set each factor = 0 and solve for cos x.