已知(x−y+3)2+2x+y=0,则x+y的值为(  ) A.0 B.-1 C.1 D.2

问题描述:

已知(x−y+3)2+

2x+y
=0,则x+y的值为(  )
A. 0
B. -1
C. 1
D. 2

(x−y+3)2+

2x+y
=0,
x−y+3=0   ①
2x+y=0  ②

①+②得3x=-3,解得x=-1,
把x=-1代入①得-1-y+3=0,解得y=2,
x=−1
y=2

x+y=-1+2=1.
故选:C.