解题方法
1 . 已知数列
各项均为正数,且
,记其前
项和为
.
(1)若数列
为等差数列,
,求数列
的通项公式:
(2)若数列
为等比数列,
,求满足
时
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
(1)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1dfe5b322577f02fd19caab8cf20170.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e31a059268c7801f786e93a76d65b68f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a8bedfcdf5e750f5451e0e5183c0d80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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解题方法
2 . 甲、乙、丙、丁四人相互做传球训练,第1次由甲将球传出,每次传球时,传球者都等可能地将球传给另外三个人中的任何一个人.则4次传球的不同方法总数为_________ (用数字作答);4次传球后球在甲手中的概率为_________ .
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3 . 已知数列
为等比数列,
,14,
成等差数列,且
.
(1)求数列
的通项公式;
(2)求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daf464629fa321a6ff7401ab79f07083.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c1496c2c8851003c73af1b0baf689fb.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0496f142d8ae5acb06e83526eaa3ef87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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4 . 甲、乙、丙三人相互做传球训练,第1次由甲将球传出,每次传球时,传球者都等可能地将球传给另外两人中的任何一人.设n次传球后球在乙手中的概率为
;
(1)求
;
(2)求
;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf83e20035c3afd6d26ebfd53d768a70.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f7807638578edd712265463a7a5eab0.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf83e20035c3afd6d26ebfd53d768a70.png)
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解题方法
5 . 已知数列
是首项是1,公比为
的等比数列,数列
的通项公式是
.设双曲线
的离心率为
且
,则当![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3cb8d72bb2e281b943b3b430138ef7.png)
________ 时,
最大.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c22c96b4d06bc3172cbeb08f4e8c4d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1eb9cfdb0458c13bd70d68248c9d8524.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/baeb2eb229c4a6a90cb1db2cfaf43177.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8f567549e66b339299dbf8369ab5812.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de43b581704cf3fbd2984340919672f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3cb8d72bb2e281b943b3b430138ef7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8f567549e66b339299dbf8369ab5812.png)
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名校
6 . 在各项均为正数的等比数列
中,
,
,
成等差数列,若
,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be78feec41e2b2ca828ee07feb8aa0c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d479842818cdc157624e4e89b708075.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2b42a580c957be7f0fe5e0de6693d69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f966272f7781790ff27e40db6b525253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb5905a1755bf66784021797d628751c.png)
A.14 | B.28 | C.42 | D.56 |
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解题方法
7 . 正三棱柱
的底面边长为1,侧棱长为2,一只蚂蚁从
点出发,每次沿着该三棱柱的一条棱的端点爬行到另一个端点,若它选择三个方向爬行的概率相等,且每次爬行都相互独立.
(1)记这只蚂蚁经过4次爬行后,其爬行的总路程为
,求
的分布列和数学期望;
(2)求这只蚂蚁经过5次爬行后,停留在平面
内的概率.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(1)记这只蚂蚁经过4次爬行后,其爬行的总路程为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
(2)求这只蚂蚁经过5次爬行后,停留在平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
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8 . 在数列
中,
,且
.
(1)若
,证明:数列
是等比数列;
(2)求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/352d9b76dcf639368fa68cae70149802.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f79b237a8e03a2ef92878e7beb86bfd.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5225dc349cd2a56194827de3f4174b9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f329b217e1051b23f0d61023cdc6e69.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2d51f9147b8265c0276c1f2c2659197.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b9a0d7150fb24be3e28ef7f0e18be93.png)
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名校
9 . 等比数列
的前
项和为
,且数列
的公比为32,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e030e6477f83384109416cbde2479bf7.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.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/051392edad70a34634b89bdac068f67f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e030e6477f83384109416cbde2479bf7.png)
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名校
解题方法
10 . 已知
为正项数列
的前n项积,且
.
(1)证明:数列
是等比数列;
(2)若
,求
的前n项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/686ece75006ad358f23314dc8a246e11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22c567a95fe6ee09e4774f64f52b116f.png)
(1)证明:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d108a155642da837f7af5c44ad7e27e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4fe99ae7973f47829463638c2c4b563.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
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