摘要:21.等差数列{an}的各项为正整数.a1=3.前n项和为Sn.等比数列{bn}中.b1=1.且b2·S2=16.b3是a1.a2的等差中项 (1)求an与bn (2)求证:
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等差数列{an}的各项为正整数,a1=3,前n项和为Sn,等比数列{bn}中,b1=1,且b2•S2=16,b3是a1、a2的等差中项
(1)求an与bn;
(2)求证:
+
+…+
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.
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(1)求an与bn;
(2)求证:
| 1 |
| S1 |
| 1 |
| S2 |
| 1 |
| Sn |
| 3 |
| 4 |
等差数列{an}的各项为正整数,a1=3,前n项和为Sn,等比数列{bn}中,b1=1,且b2•S2=16,b3是a1、a2的等差中项
(1)求an与bn;
(2)求证:
+
+…+
<
.
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(1)求an与bn;
(2)求证:
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等差数列{an}的各项均为正数,a1=3,前n项和为Sn,{bn}为等比数列,b1=1,且b2S2=64,b3S3=960.
(1)求an与bn;
(2)若不等式
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+…+
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对n∈N*成立,求最小正整数m的值.
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(1)求an与bn;
(2)若不等式
| 1 |
| S1 |
| 1 |
| S2 |
| 1 |
| Sn |
| m-2009 |
| 4 |