若(y+2)²+x²-6x=-9,则x+y的值是

若(y+2)²+x²-6x=-9,则x+y的值是
若(y+2)²+x²-6x=-9,则x+y的值是

若(y+2)²+x²-6x=-9,则x+y的值是
若(y+2)²+x²-6x=-9,则x+y的值是1
若(y+2)²+x²-6x=-9,
则(y+2)²+(x²-6x+9)=0
(y+2)²+(x-3)²=0
y+2=0 y=-2
x-3=0 x=3
x+y=3-2=1

(y+2)²+x²-6x=-9
(y+2)²+x²-6x+9=0
(y+2)²+(x-3)²=0
∴y+2=0
x-3=0
解这个方程组得
x=3
y=-2
∴x+y=3-2=1

(y+2)²+x²-6x=-9,
(y+2)²+x²-6x+9=0
(y+2)²+（x-3）²=0
y=-2,x=3
x+y=1