右边移过来(x²-2x+1)+(4y²-4y+1)+√(-z²)=0(x-1)²+(2y-1)²+√(-z²)=0平方和根号都大于等于0相加为0则都是0x-1=0,2y-1=0,-z²=0x=1,y=1/2,z=0所以√(x+2y-z)=√2...