(x+x^2+.+x^n-n)/(x-1)求极限
3个回答

x→1?因式分x^k-1=(x-1)[x^(k-1)+x^(k-2)+……+x+1]x+x^2+……+x^n-n=(x-1)+(x^2-1)+……+(x^n-1)=(x-1)[1+(x+1)+……+(x^(n-1)+x^(n-2)+……+x+1)]所以lim(x→1) (x+x^2+……+x^n-n)...