Question

Решите уравнение 4cosx+2=0

Answer 1

4cosx=-2
Cosx=-2/4
cosx=-1/2
X=+-arccos(-1/2)+2Пn
x=+-(П-arccos(1/2))+2Пn
X=+-5П/6 + 2Пn

Answer 2

$4cosx=2 \\ cosx=- \frac{1}{2} \\ x=+- \frac{2 \pi }{3}+2 \pi k$

k∈Z