( )+x^2-xy+2y^2=2x^2+xy+3y^2
(xy-x^2)乘以(xy)/(x-y)
计算:3xy[2xy-x(y-2)+x]
(-3x^y+2xy)-( )=4x^+xy
(x+2y-3xy)-(-2x-y+xy),其中x+y=,xy=-,求值.
(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)
已知x-y=4xy,则2x+3xy-2yx-2xy-y
xy(xy+1)+(xy+3)-2(x+y+2分之一)-(x+y-1)的平方
(x^2+xy/x-y)/(xy/x-y)计算
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少?
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