题目抄漏了,还应该有+4,即x²-2xy+2y²-4y+4=0x²-2xy+2y²-4y+4=0(x²-2xy+y²)+(y²-4y+4)=0(x-y)²+(y-2)²=0平方项恒非负,两非负项之和=0,两非负项分别=0x-y=0 y-2=0解得x=...