1/2*sin(2π/3-4x)≥√3/4
sin(2π/3-4x)≥√3/2
sin(4x-2π/3≤-√3/2
4π/3+2πn≤4x-2π/3≤5π/3+2πn
2π+2πn≤4x≤7π/3+2πn
π/2+πn/2≤x≤7π/12+πn/2,n∈z
1/2≤cos(2x-π/3)≤1
-π/3+2πk≤2x-π/3≤π/3+2πk
2πk≤2x≤2π/3+2πk
πk≤x≤π/3+πk
(1-cosa)(1+cosa)=1^2-cos^2a=1-cos^2a=sin^2a
А
1)1,4*3,6=5,04
2)5,04/0,2=25,2
3)25,2-4,2=21
4)3/4:1/5=3/4*5=15/4=3,75
5)3,75-0,25=3,5
6)21:3,5=21*2/7=6
б
1)3,2*2,3=7,36
2)7,36/0,4=18,4
3)18,4-4,4=14
4)2/3*1/3=2/9
5)2/9+5/9=7/9
6)14:7/9=14*9/7=18