(1)-3x²y+2x²y+3xy²-2xy²
已知x=3 y=1\3,求3x²y-[2xy²-2﹙xy-3\2x²y﹚+xy]+3xy&
下列多项式:(1)x²+xy-y²;(2)-x²+2xy-y²;(3)xy+x&
(3x+2y)(9x²-6xy+4y²﹚
[xy(x²-3y)+3xy²]﹙﹣2xy﹚+x³y²﹙2x-y﹚ 其中x=﹣1
1.若x/y=2,求分式x²-xy+3y²/x²+xy+6y²的值
已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
(2x²y-3xy²)-3(x²y-2xy²)+2(x²y-4xy
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
化简求值3x²y-[2xy-2(xy-3/2x²y)+xy]+3xy²其中x=3、y=-1
先化简,再求值 4(xy²+3xy-2x²y)-[12xy-3(3x²y-2xy²
2x²y+{2xy-[x²y-2(﹣3x²y+xy)]﹣4xy²} 计算