(1)(2x+y-z+10)(2x-y+z+10)
=[2x+10+(y-z)](2x+10-(y-z)]
=(2x+10)²-(y-z)² 你说的是这样吗?是的话我继续打
(2)(a+b)^2(a-b)^2-(a^2+b^2)(a-b)
(3)^2-^2
(4)(a-b-c)^2
(5)(x+2y-2/3)(x-2y+2/3)　　是，继续打