Question

Решите неравенство
$2cos^{2} 2x geq 1,5$

Answer 1

2*(1+cos4x)/2≥3/2
2+2cos4x≥3
2cos4x≥1
cos4x≥1/2
-π/3+2πn≤4x≤π/3+2πn
-π/12+πn/2≤x≤π/12+πn/12
x∈[-π/12+πn/2;π/12+πn/2]