已知数列{an}的前n项和伟Sn,且a1=1,na（n+1）=（n+2）Sn,n属于N* 求证数列{Sn/n}为等比数列求数列{an}的通项公式及前n项和Sn;若数列{bn}满足：b1=1/2,bn+1/n+1=bn+Sn/n+1(n属于N*）,求数列{bn}的通项公式

已知数列{an}的前n项和伟Sn,且a1=1,na（n+1）=（n+2）Sn,n属于N* 求证数列{Sn/n}为等比数列求数列{an}的通项公式及前n项和Sn;若数列{bn}满足：b1=1/2,bn+1/n+1=bn+Sn/n+1(n属于N*）,求数列{bn}的通项公式
已知数列{an}的前n项和伟Sn,且a1=1,na（n+1）=（n+2）Sn,n属于N* 求证数列{Sn/n}为等比数列
求数列{an}的通项公式及前n项和Sn;
若数列{bn}满足：b1=1/2,bn+1/n+1=bn+Sn/n+1(n属于N*）,求数列{bn}的通项公式

已知数列{an}的前n项和伟Sn,且a1=1,na（n+1）=（n+2）Sn,n属于N* 求证数列{Sn/n}为等比数列求数列{an}的通项公式及前n项和Sn;若数列{bn}满足：b1=1/2,bn+1/n+1=bn+Sn/n+1(n属于N*）,求数列{bn}的通项公式
1） 证明：
na[n+1] = (n+2)S[n]
n(S[n+1]-S[n]) = (n+2)S[n]
nS[n+1] = 2(n+1)S[n]
S[n+1]/(n+1) = 2*S[n]/n,(首项=S[1]/1=a[1]/1=1)
所以：{S[n]/n}是以1为首项,公比为2的等比数列
S[n]/n = 1 * 2^(n-1)
S[n] = n*2^(n-1)
a[n] = S[n]-S[n-1] = n*2^(n-1) - (n-1)*2^(n-2)
= (2n-(n-1))* 2^(n-2) = (n+1)*2^(n-2)
3) 看不懂 加几个括号会死啊

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站立,光波炉菜谱，双脚分开与胯同宽,盟特新产品加盟，双臂充分前伸，抓紧毛巾下蹲，然后慢慢恢复站立姿势。
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站立,光波炉菜谱，双脚分开与胯同宽,盟特新产品加盟，双臂充分前伸，抓紧毛巾下蹲，然后慢慢恢复站立姿势。
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保持与上组运动同一的姿势，把毛巾套在右足趾与足心处，上勾右足,加湿器，右腿向上伸直。双手向下拉紧毛巾，同时向上伸展右足重复伸展,盟特新产品厂家，勾起右足15次。

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对于很多office lady来说一天可能会在办公室坐上八个小时甚至更多的时间,加湿器厂家，慢慢地会发现大腿越来越粗壮，其实只要认清你大腿的问题真正出在哪里?用一些简单的运动甚至改变坐姿,光波炉厂家，都可以达到阻止大腿变粗的效果……一起来看看吧?
柔软结实的肌肉,红外线光波炉，是塑造美腿的前提,光波炉，透过下面介绍的各式柔软运动操，每天持之以恒练习，不仅能改善原本不完美的腿形，还可让它更漂亮、更修长。
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