x的2次方+y的2次方-4x+6y=13=0 (x²-4x+4)+(y²+6y+9)=0 (x-2)²+(y+3)²=0 x=2 y=-3 x+y=2-3=-1 祝学习进步,望采纳~~ 不懂的欢迎追问~~,7,-1,1,x²+y²-4x+6y+13=0 (x-2)²+(y+3)²=0 由非负性 x-2=0 y+3=0 解得 x=2 y=-3 故 x+y =2-3 =-1,0,