(y²+6y)²-y(6+5y)(6-5y)+y²(12y-y²)= 5(а+1)(а-1)-10а = 3х(х-2)-(х-3)² = (b-5)(b-4)-3b(2b-3) = Решите плиз, проверяю

1)=у⁴+12у³+36у²-у(36-25у)+12у³-у⁴=у⁴+12у³+36у²-36у+25у²+12у³-у⁴=24у³+61у²-36у; 2)=5а²-5-10а ; 3)=3х²-6х-х²+6х-9=2х²-9; 4)=b²-4b-5b+20-6b²+9b=-5b²+20