Sin3x=2sinx
<span>sin(3x) - 2sin(x) = 0
sin(3x) = 3sin(x) - 4sin^3(x)
3sin(x) - 4sin^3(x) - 2sin(x) = 0
-4sin^3(x) + sin(x) = 0 |: (-1)
4sin^3(x) - sin(x) = 0
sin(x)*(4sin^2(x) - 1) = 0
sin(x) = 0
sin(x) = 0
x = πn,n∈Z
4sin^2(x) = 1
sin^2(x) = 1/4
</span>(1-cos2x)/2=1/4
1-cos2x=1/2
cos2x=1/2
2x=+-π/3+2πk,k∈Z
x=+-π/6+πk,k∈Z
(3x-6y)-(-6x+2y)
вроде бы так, просто раскрыть скобки