x-y+3的绝对值与(x+y-2013)的平方互为相反数
∴│x-y+3│+(x+y-2013)²=0
∴﹛x-y+3=0
x+y-2013=0
解得x=1005,y=1008
∴x+2y/x-y
=(1005+2×1008)/(1005-1008)
=-1007