(1)-4x²yz-12xy²z+4xyz(2)-1/2-x²-y³+2x²y^4z(3)(a+b)²-(a+b)
(4)6(m+n)²-2(m+n)(5)x(x-y)(a-b)-y(y-x)(b-a)
(6)2x(1+a²)-1-a²(7)32a^5b^4-16a^3b^5+24a^b^4
(8)a(1-a)-(a-1)^2