2 sin² 4x-4(sin^2x+cos^2x)=3sin 4x cos4x-4 cos² 4x
2sin^2x-4sin^2 4x-4cos^2 4x-3sin4xcos4x+4cos^2 4x=0
-2sin^2 4x-3sin4xcos4x=0
sin4x(2sin4x+3cos4x)=0
sin4x=0 или 2sin4x+3cos4x=0
4x=pi n 2tg4x+3=0
x=1/4pi n tg4x=-3/2
4x=-arctg3/2+ pi k
x=-1/4arctg3/2+ 1/4pi k
n,k eZ