x^2+2x+y^2-6y+10=0
(x^2+2x+1)+(y^2-6y+9)=0
(x+1)^2+(y-3)^2=0
因为(x+1)^2≥0,(y-3)^2≥0
所以x+1=0,y-3=0
x=-1,y=3
x^2+2y=1+6=7