设{a
n}是首项为a,公差为d的等差数列(d≠0),S
n是其前n项和.记
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124332914831541/SYS201310251243329148315018_ST/0.png)
,n∈N
*,其中c为实数.
(1)若c=0,且b
1,b
2,b
4成等比数列,证明:
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124332914831541/SYS201310251243329148315018_ST/1.png)
(k,n∈N
*);
(2)若{b
n}是等差数列,证明:c=0.
考点分析:
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n}中,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124332914831541/SYS201310251243329148315013_ST/0.png)
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1+a
2+…+a
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1a
2…a
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