3x(-y-xy²+x²)

x²/xy-x/y 计算：(xy-x²)×x-y/xy (x-y)²-(3x-3xy+y²)因式分解 3x²y+xy²-[2xy²-4x²y+（x²y-2xy²） (2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy&# (3xy)² · (x²+xy-y²)-3xy(3x³y+3x²y&# [-xy/(x-y)²]²×(y²-xy/x)³ 先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y x/xy-y²与y/x²-xy 通分 x-y/x²÷x²-2xy+y²/xy*（xy-x²） 计算3x[xy-2x(1/y-x/3]+3y(x²-y²) -3(xy-2x²)-[y²-(5xy-4x²)+2xy]