Решение
3cos(x/4 - π/4) ≥ 3/2
cos(x/4 - π/4) ≥ 1/2
cos(x/4 - π/4) ≥ 1/2
- arccos(1/2) + 2πn ≤ x/4 - π/4 ≤ arccos(1/2) + 2πn, n∈z
- π/3 + 2πn ≤ x/4 - π/4 ≤ π/3 + 2πn, n∈z
- π/3 + π/4 + 2πn ≤ x/4 ≤ π/3 + π/4+ 2πn, n∈z
- π/12 + 2πn ≤ x/4 ≤ 7π/12 + 2πn, n∈z
- π/3 + 8πn ≤ x ≤ 7π/3 + 8πn, n∈z
tg²x + tgx - 2 = 0
1) tgx = 1
x₁ = π/4 + πk, k∈z
2) tgx = - 2
x₂ = arctg(-2) + πn, n∈Z
x₂ = - arctg2 + πn, n∈Z