Solve the equation on the interval [0,2π). 8cos^2x+4cosx=0 Select all correct solutions. 0 π/3 π/2 2π/3 π 4π/3 5π/3 3π/2 11π/6

Question

asked Jan 8, 2023 60.9k views

2 Answers

Frolik · Answer 1 · 2023-01-14T10:19:20+0000

Answer:

π/2, 2π/3, 3π/2, 4π/3.

Explanation:

8cos^2x+4cosx=0

4cosx(2cosx + 1) = 0

so cosx = 0, -1/2.

Therfore

When cos x = 0:

x = π/2, 3π/2

When cos x = -1/2:

x = 2π/3, 4π/3.