( )·(-2xy)=4x²y-6xy²
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
计算;(xy-x²)÷x²-2xy+y²/xy · x-y/x²
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
已知2x²+xy=6,3y²+2xy=9,求4x²+8xy+9y²的值为( )
先化简,再求值:4x²y-【6xy-2(4xy-2)-xy²】+1.其中x=-二分之一,y=2.
已知x+xy=-2,xy-y=-6求代数式2x{-4y-3[(x+xy)²+x]-½[(y-xy
已知x/2=y/3(xy≠0),求x²-2xy-3y²/x²-6xy-7y²的值
已知x+y=4,xy=-2,求代数式3(xy+2y)-(xy-6x)
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
化简求值 已知:(x+2)2;+|y+1|=0求5xy²-{2xy²-[3xy²(4xy&
(1)先化简,再求值:[4(xy-1)²-(xy+2)(2-xy)]÷1/4xy,其中x=-2,y=1/5.