cos 2u = 2 cos2u - 1
Substitute
4 cos2u - 2 + 3 cos u - 5 = 0
4cos2u + 3 cos u - 7= 0
This is a quadratic is cos u.
Quadratic formula gives an extraneous root and cos u =1
This means u = 0 and multiples of 2 pi.
Kelsie B.
asked • 12/12/19Find all solutions of the equation: 2 cos2 u + 3 cos u − 5 = 0. Use exact values.
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