2x^2-3xy+(-y^2)-2x^2-(-5xy)+2y^2=?
计算:3xy[2xy-x(y-2)+x]
(x+2y-3xy)-(-2x-y+xy),其中x+y=,xy=-,求值.
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
xy(xy+1)+(xy+3)-2(x+y+2分之一)-(x+y-1)的平方
(xy-x^2)乘以(xy)/(x-y)
利用x-y=3^2009,xy=-3^2010,求代数式:(2x+3y-2xy)-(x+4y+xy)-(3xy+2y-2
已知x-y=4,xy=-2,求代数式(2x+3y-2xy)-(x+4+xy)-(3xy+2y-2x)的值
已知x+xy=-2,xy-y=-6求代数式2x{-4y-3[(x+xy)²+x]-½[(y-xy
(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)
(-3x^y+2xy)-( )=4x^+xy
化简!1、(x^2-xy)+xy+y^2 2、3(x^2-xy)-xy+y^2
已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2