已知数列
是公比大于0的等比数列,
,其前4项的和为120.
(1)求数列
通项公式;
(2)记
,
,求数列
前
项和.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30ae7c6918ce23abc50e28ca7aa8eba4.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(2)记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dabfc022622c58033ea5a6d7ab99227d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e145b6046bc80d0ffecc61ac67c87ca1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c3b1101b78047db93954629de593a8e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
更新时间:2023-09-29 13:32:24
|
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(1)求
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(2)设数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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【推荐2】已知数列
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(1)若
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【推荐1】从下面两个条件中选择一个填在横线上并完成解答.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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【推荐1】在等比数列
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|
较易
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名校
【推荐2】已知等比数列
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