若x+y=4,则多项式1/2(x+y)+4(x-y)-3(x-y)-3/2(x+y)-x+y值是()

问题描述:

若x+y=4,则多项式1/2(x+y)+4(x-y)-3(x-y)-3/2(x+y)-x+y值是()

1/2(x+y)+4(x-y)-3(x-y)-3/2(x+y)-x+y=X/2+Y/2+4X-4Y-3X+3Y-3/2X+3/2Y-X+Y=(1/2+4-3-3/2-1)X+(1/2-4+3+3/2+1)Y=-X+2Y

原式=-x-y=-(x+y)=-4

1/2(x+y)+4(x-y)-3(x-y)-3/2(x+y)-x+y=1/2(x+y)+(x-y)-3/2(x+y)-(x-y)=-(x+y)=-4