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设等比数列{an}的公比q=2,前n项和为Sn,则=( ) A.2 B.4 C....
设等比数列{a
n}的公比q=2,前n项和为S
n,则
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=( )
A.2
B.4
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225323511320852/SYS201311012253235113208004_ST/1.png)
D.
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选做题:不等式选讲
(Ⅰ) 设a
1,a
2,a
3均为正数,且a
1+a
2+a
3=m,求证
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+
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≥
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.
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2+by
2≥(ax+by)
2.
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