已知数列
的前
项和为
,且
.
(1)求数列
的通项公式;
(2)设
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62574e80053a87d6276e2faae9666612.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/526c62fcc88b82a7a7e5384f4973eb00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/915f4eeb65f99ad54800f4624eba1032.png)
更新时间:2018-02-05 18:12:45
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【推荐1】已知数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/407b24ddd0f08e161027d1f51d355107.png)
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(2)设
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4ff128b22e3abab2ba8f4d3012c33ee.png)
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解答题-问答题
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适中
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【推荐2】袋中有大小形状均相同的1白球、2黑球,现进行摸球游戏,约定摸出白球得2分,摸出黑球得1分.
(Ⅰ)现约定有放回地摸球4次,得分为X,求变量X的分布列和数学期望;
(Ⅱ)当游戏得分为n(n∈N*)时,游戏停止,记得n分的概率为Qn,Q1=
.
(ⅰ)求Q2;
(ⅱ)若Tn=Qn+1﹣Qn,求数列{Tn}的通项公式.
(Ⅰ)现约定有放回地摸球4次,得分为X,求变量X的分布列和数学期望;
(Ⅱ)当游戏得分为n(n∈N*)时,游戏停止,记得n分的概率为Qn,Q1=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
(ⅰ)求Q2;
(ⅱ)若Tn=Qn+1﹣Qn,求数列{Tn}的通项公式.
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解答题-问答题
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【推荐1】已知等差数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4c5225f6c9fb795e5f3e3b113abea8.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7830618de3980d629724a49b3dc3860.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)令
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2e7f395bf18282eb4d8a27c416d8660.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4995fa0403e013d888c0935ebfe15024.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c1d3c0e668468adc3108c788cf701b9.png)
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【推荐2】已知数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9253eb4b892b8ae34fd6baf4b02460d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b94fe46dc2275759b853bae34993032.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3df968c2121537f9d2188cda8d296add.png)
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