Sin^4 x*Cos^2 x-Cos^4 x * Sin^2 x = Cos2x

Sin (x) ^4 cos (x) ^2 - cos (x) ^4 sin (x) ^2 = cos (2x)

sin (x) ^2 cos (x) ^2 [ sin (x) ^2 - cos (x) ^2 ] = cos (2x)

- sin (x) ^2 cos (x) ^2 cos (2x) = cos (2x)

cos (2x) [ 1 + sin (x) ^2 cos (x) ^2 ] = 0

1 + sin (x) ^2 cos (x) ^2 = 0

(sin (x) cos (x)) ^2 = - 1

Решений нет

cos (2x) = 0

2x = п/2 + пк

x = (п/4) (2k + 1)