(x-y)^3=x³--3x²y+3xy²-y³ 得 -3x²y+3xy=²(x-y)^3-(x³-y³)原式=x(x³-y³)+(x-y)^3-(x³-y³)+y(y³-x³)=(x³-y³)(x-y-1)+(x-y)^3X-y=1...