（x+y+2）的平方+2x-3y-1的绝对值=0由非负性x+y+2=0........(1)2x-3y-1=0........(2)(1)*3+(2)得5x+5=0x=-1代入(1)得-1+y+2=0y=-1解得x=-1y=-1则x+y=-1-1=-2
