Question

Помогите плииииз 8cos^2x+5cosx-3=0

Answer 1

$8cos^2x+5cos x-3=0\ (cos x+1)(8cos x-3)=0\ left{begin{matrix} cos x = -1\ cos x = frac{3}{8} end{matrix}right\ left{begin{matrix} x = pi + 2pi k\ x = 2pi kpm arccosfrac{3}{8} end{matrix}right$