1)y( y-1)+x(1-y)=(y-1)(y-x)
2)a(a-1)+x(1-a)=(a-1)(a-x)
3)a(3a+1)+b(3a+1)=(3a+1)(a+b)
4)5a(a-x)-7(a-x)=(5a-7)(a-x)
5) 3m^2n(2m^2+4m+1)
6)2a^3b(a^2-2a+1)=2a^3b(a-1)^2
7)(a-b)^2-y^2=(a-b-y)(a-b+y)
8)(a^2-b^2)^2
9)(x-4)(x+8)
10)2(x-3)^2
11)2(x-1.5)(x-1)
12)(x+2)(x-1)