丨x+1丨=(x-y+3)²=0x+1=0 x=-1x-y+3=0 -1-y+3=0 y=2(x+y)²=(-1+2)²=1选 B
丨x+1丨=(x-y+3)²=0丨x+1丨≥0且(x-y+3)²≥0所以丨x+1丨=0且(x-y+3)²=0x+1=0且x-y+3=0所以x=-1 y=2(x+y)²=(-1+2)²=1选B
|x+1|=0x+1=0x=-1(x-y+3)²=0x-y+3=0y=x+3=-1+3=2(x+y)²=(-1+2)²=1选B
B