cos^4a+cos^2asin^2a+sin^2a+tg^2a=cos^2a(cos^2a+sin^2a)+sin^2a+tg^2a=
(2x+y)³-6xy(2x+y)=(2х)³+3·(2х)²у+3·2ху²+у³-12х²у-6ху²=
(18 - 6 x + x^2) (18 + 6 x + x^2)