901- 1)(3а-2в)²-(а+в)² 2)(2м-n)²-(m+n)² 902- 1)4(a-b)²-(a+b)² 2)9(a-b)²-4(x-y)²

1)(3a-2b)²-(a+b)²=(9a²-12ab+4b²)-(a²+2ab+b²)=
=9a²-a²-12ab-2ab+4b²-b²=8a²-14ab+3b²
2)4(a-b)²-(a+b)²=4(a²-2ab+b²)-(a²+2ab+b²)=
=4a²-a²-8ab-2ab+4b²-b²=3a²-10ab+3b²
3)9(a-b)²-4(x-y)²=(3(a-b))²-(2(x-y))²=(3a-3b)²-(2x-2y)²=
=(3a-3b+2x-2y)(3a-3b-2x+2y)