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