1)2х-2+6-3х=-х+4
2)7m^2-7mn-3n^2-3mn=7m^2-3n^2-10mn
3)x^2+2xy-2xy+y=x^2+y
4)x^3+2yx^2-2yx^2-y=x^3-y
5)6ab-4a^2b+12ab-28a^2b=18ab-32a^2b
6)2yx^2 -4xy^2-28yx^2=-4xy^2-26yx^2
7)x^2-2xy-5y+10x
8)x^3-xy^2+xy^2-y^3=x^3-y^3
9)(x^2+2xy+y^2)(x-1)-(x^2--2xy+y^2)x=x^3+2yx^2-xy^2-x^2-2xy-y^2-x^3+2yx^2-xy^2=-x^2-y^2+4yx^2-2xy