展开全部
1+1/(1+2)+1/(1+2+3)+...+1/(1+2+3...+n)
=1+1*2/(2*3)+1*2/(3*4)+...+1*2/[n*(1+n)]
=2[1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/n-1/(n+1)]
=2[1/2+1/2-1/(n+1)]
=2-2/(n+1)
=2n/(n+1)
=1+1*2/(2*3)+1*2/(3*4)+...+1*2/[n*(1+n)]
=2[1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/n-1/(n+1)]
=2[1/2+1/2-1/(n+1)]
=2-2/(n+1)
=2n/(n+1)
已赞过
已踩过<
评论
收起
你对这个回答的评价是？
推荐律师服务：
若未解决您的问题，请您详细描述您的问题，通过百度律临进行免费专业咨询
