已知y-2x=-2010,xy=10,求2x^4y^3-x^3y^4的值

已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知2x+xy=10,3y+2xy=6.求4x+8xy+9y=? 已知x+y=3,xy=-10,求（1）x平方-xy+y平方；（2）|x-y| 已知x+y=-2,求代数式(6xy+10y)+[4x-2(3xy+2y-x)] 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>0,y>0,且x- 10√xy+25y=0,求2x+√xy+3y/x+√xy-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:y=3:2,求(x²+3xy)/(xy+2xy) 已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2 已知:x/y=-2,求x^2-2xy-3y^2/x^-6xy 已知:x-xy=40,xy-y=-20,求代数式x-y和x+y-2xy的值. 已知x-xy =21,xy-y=-12,分别求式子x-y与x-2xy +y 已知y=3xy+x,求代数式2x+3xy-2y/x-2xy-y的值 已知x+y=3xy,求2x+2y-xy/x+y+2xy的值、 已知x-y/xy=3,求分式2x+3xy-2y/x-2xy-y的值. 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y)