x²-（x-y）²=x²-x²+2xy-y²=2xy-y²（x+2y）²-（2x-y）²=x²+4xy+4y²-4x²+4xy-y²=3y²+8xy-3x²（x+y+z）²-（x-y-z）²=(x+y+z-x+y+z)(...能把他修改改成分解因式的形式么，我在给你加10~20分··可以。x²-（x-y）²=(x-x+y)(x+x-y)=y*(2x-y)=2xy-y²（x+2y）²-（2x-y）²=(x+2y-2x+y)(x+2y+2x-y)=(3y-x)(3x-y)=9xy-3x²-3y²-xy=8xy-3x²-3y²（x+y+z）²-（x-y-z）²=(x+y+z-x+y+z)(x+y+z+x-y-z)=(2y+2z)*2x=4xy+4xz（a-b） ^4-（b-a）²=(a-b)²[(a-b)²-1)=(a²-2ab+b²)(a²-2ab+b²-1)=a^4-2a³b+a²b²-a²-2a³b+4a²b²-2ab³+2ab+a²b²-2ab³+b^4-b²=a^4-4a³b+6a²b²-a²-4ab³-b²+^4