x/(x-1)^2=x(x²+x+1)/(x-1)(x³-1)=（x³+x²+x）/(x-1)(x³-1)
2/1-x^3=2（1-x）/(x-1)(x³-1)=(2-2x)/(x-1)(x³-1)又是你，速度好快啊，