2(a-b)+a(a-b)=
7(x+y)-a(x+y)=
2(a-b)+c(b-a)=
2a(b-3)-5c(3-b)=


(m+1)-m(m+1)=
x(y-z)²+(z-y)²=
4(m+n)+(m+n)=
2(x-y)-a(x-y)=

1) 2a-2b+a^2-ab
2) 7x+7y-ax-ay
3) 2a-2b+cb-ca
4) 2ab-6-15 c-5cb


1)(m+1)-(m^2-1 )= (m+1)-(m-1)(m+1)=m-1