bret4325 bret4325 23-01-2024 Mathematics contestada Use the drop-down menu to choose the appropriate substitution. -cos^2(x) - 4cos(x) + 5 = 0, let u =... a) -cos(x) + 1 b) cos(x) - 5 c) cos(x) + 5 d) cos(x) - 1