是x²-x-2xy+y+y²=0吧，若不是，就追问吧 解：x²-x-2xy+y+y²=0（x-y)²-(x-y)=0(x-y)(x-y-1)=0x-y=0,或x-y=1 ½（x²+y²）-xy=½（x²+y²）-1/2*2xy=1/2(x²+y²-2xy)=1/2(x-y)²=0或1/2
