已知y-x=3xy 求2x+5xy-2y/x-2xy-y已知分式x(x-3)/(x^2+1)的值为零,则2x/(x^2-1)÷3x/(1-x)的值为多少,

已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2 已知X-XY-2Y=0求2X+3XY-Y/X-2XY+5Y 已知xy/x+y=3,求代数式2x-5xy+2y/x-3xy+y 已知xy/x+y=2,求代数式3x-5xy+3y/-x+2xy-y的值 已知Y-x=3xy,求(5x+3xy-5y)÷(x-2xy-y) 已知X+Y分之XY=2,求-X+3XY-Y分之3X+5XY+3Y 已知xy=2(x+y),求(5x-xy+5y)/(3xy-x-y)的值 已知xy=2(x+y),求5x-xy+5y/3xy-x-y的值 已知x-y=3xy,求5x+2xy-5y/x-4xy-y的值 已知xy/x+y=2,求代数式8x-5xy+8y/-x+3xy-y的值 已知xy^2=-2求xy（2x^3y^7+5x^2y 已知xy/x+y=2,求代数式3x-5y+3y/-x+3xy-y 已知xy/(x+y)=2求(3x-5y+3y)/(-x+3xy-y) 已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理.已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理. 已知x^+xy=-5,xy+y^=8,求2x^-xy-3y^的值都是2次 已知x—xy=5,xy—y=-3,求x+y—2xy的值.