先化简,:(-三分之一xy)^2【xy(2x-y)-2x(xy-y^2)】
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
计算:3xy[2xy-x(y-2)+x]
分解因式:(X+Y)*(X+Y+2XY)+(XY+1)*(XY-1)
xy(xy+1)+(xy+3)-2(x+y+2分之一)-(x+y-1)的平方
化简求值:(负三分之一 xy)²[xy(2x-y)-2x(xy-y²)],其中x=-一又二分之一,y
化简!1、(x^2-xy)+xy+y^2 2、3(x^2-xy)-xy+y^2
(xy-x^2)乘以(xy)/(x-y)
① 先化简,再求值.【2x(xy-xy)+xy(xy-x)】÷xy,其中x=2013,y=2012
x根号x+x根号y/xy-y^2)-(x+根号xy+y/x根号x-y根号)y
(x+2y-3xy)-(-2x-y+xy),其中x+y=,xy=-,求值.
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
计算;(xy-x²)÷x²-2xy+y²/xy · x-y/x²