9x(-2x^2-xy+y^2)•(-xy)
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
计算:3xy[2xy-x(y-2)+x]
9x(-2x^2-xy+y^2)•(-xy)
(xy-x^2)乘以(xy)/(x-y)
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
(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)
化简!1、(x^2-xy)+xy+y^2 2、3(x^2-xy)-xy+y^2
x根号x+x根号y/xy-y^2)-(x+根号xy+y/x根号x-y根号)y
计算;(xy-x²)÷x²-2xy+y²/xy · x-y/x²
(xy-x²)除以xy分之x²-2xy+y²乘以x²分之x-y
(x+2y-3xy)-(-2x-y+xy),其中x+y=,xy=-,求值.