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