Question

Cos 7x-cos x=0 РЕШИТЕ ПОЖАЛУЙСТА

Answer 1

cos7x - cosx = 0
- 2sin(7x + x)/2 * sin(7x - x)/2 = 0
sin4x * sin3x = 0
1)  sin4x = 0
4x = πk, k∈Z
x₁ = πk/4, k∈z
2) sin3x = 0
3x = πn, n∈Z
x₂ = πn/3, n∈Z