①3x²+6xy+3y²
合并同类项:(2xy²+3xy²)-(6x²y-3xy²)
已知x/y=2,求x²-xy+3y²/x²+xy+6y²的值
3x-2xy-8-2x+6xy-x²+6、-x²+2xy-y²-3x²-2xy+
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
(2x²y-3xy²)-3(x²y-2xy²)+2(x²y-4xy
(3xy)² · (x²+xy-y²)-3xy(3x³y+3x²y
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
1.x-y=16,xy=6,求3x²y-6xy²+18y+6
已知xy²=-6,求xy(x^3y^7-3x^2y^5-11.5y)的值
(x-y)²-(3x-3xy+y²)因式分解
已知x/2=y/3(xy≠0),求x²-2xy-3y²/x²-6xy-7y²的值
1 、x+y=8 xy=6 求x²+3xy+2y²/x²y+2xy²