-2y³+(3xy²-x²y)-2(xy²-y³)
-2y³+(3xy²-x²y)-2(xy²-y³)
计算:(-7x²y)(2x²y-3xy³+xy)
计算:x²y-(2xy²-5x²y)+3xy²-y³
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
计算[xy(x²-3y)+3xy²]·(-2xy)+x³y²(2x-y)
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
计算(2x³-3x²y-2xy²)-(x³-2xy²+y³)
(2x³- 3x²y -2xy²)-(x³- 2xy²+y³
无论x,y取何值时,代数式:(x³+3x²y-5xy+6y³)+(y³+2xy&
(-2/3X³y+4x²y²-1/2xy²)/(-xy/4) 急