(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)
=2x+y-2xy-3x-2y-xy-4xy-3y+5x
=4x-4y-7xy
=4(x-y)-7xy
因为x-y=4,xy=1
所以
原式=4*4-7=16-7=9