x²+y²-2x+6y+10=0
(x-1)²+(y+3)²=0 由于平方都是≥0的,此处=0.则每一个都要是0,
所以x-1=0且y+3=0
所以x=1,y=-3 x+y=-2
X²+y²-2X+6y+10=0
X²-2X+1+y²+6y+9=0
(X-1)²+(y+3)²=0
X-1=0 y+3=0
X=1 y=-3
X+y=-2
x2+y2-2x+6y+10=0
(x2-2x+1)+(y2+6y+9)=0
(x-1)2+(y+3)2=0,左边为非负式
x=1,y=-3,x+y=-2
x^2+y^2-2x+6y+10=0
(x-1)^2+(y+3)^2=0
x=1 and y=-3
x+y= 1-3 =-2