f(x)=(x^5-x^3+x^3-x+x)/(x^2-1)=x^2+x+x/[(x+1)(x-1)]=x^2+x+1/2(1/(x+1)+1/(x-1))因为(1/x)^(n)=(-1)^n*n!/x^(n+1)且(x^m)^(n)=0 (n>m)所以f(x)^(5)=1/2((-1)^5*5!/(x+1)^6+(-1)^5*5!/(x-1)^6)=-60(1/(x+1)^6+1/(x-1)^6)
