2X+5Y与4X-4Y的一半的差是
A.X-Y B.Y-X C.X-9Y D.7Y
2X+5Y-(4x-4y)/2
(4x-4y)提取2,再约分,得2x+5y-2x+2y=7y
选D
2X+5Y-1/2(4X-4Y)=2X+5Y-2X+2Y=7Y
答案是D
d
选D,