题目错误,分子应该是3X+XY-3Y分子分母同除以XY分子=(3X+XY-3Y)/XY=3X/XY+XY/XY-3Y/XY=3/Y+1-3/X=-3(1/X-1/Y)+1=-3*2+1=-5分母=(X-XY-Y)/XY=X/XY-XY/XY-Y/XY=1/Y-1-1/X=-(1/X-1/Y)-1=-2-1=-3所以原式=(-5)/(-3)=5/3...