1. b²(a-1)-c(1-a)=b²(a-1)+c(a-1)=(a-1)(b²+c)
2. a²(m-2)+b(2-m)=a²(m-2)-b(m-2)=(m-2)(a²-b)
3. a(b-c)+b²(b-c)=(b-c)(a+b²)
4. x(x-y)+y(y-x)-2(x-y)=(x-y)(x-y-2)
5. x(a-2)+y(2-a)+(2-a)=(2-a)(1+y-x)
6. a(b-3)+(3-b)=(b-3)(a-1)
