名校
1 . 已知数列{an}的前n项和Sn满足:Sn=2n2-20n+1.
(1)求数列{an}的通项公式;
(2)求使得Sn取最小值时的n的值.
(1)求数列{an}的通项公式;
(2)求使得Sn取最小值时的n的值.
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解题方法
2 . (本小题满分16分)
已知数列
的前
项和为
,且满足
,数列
的前
项和为
,且满足
,其中
N*.
(1)求数列
的通项公式;
(2)若数列
是公差不为零的等差数列.
①求实数
的值.
②若
≤
对任意的
N*恒成立,求
的取值范围.
已知数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.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/60965815aa04043db051b7bd89eda80d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0213618a5d387fe37099f954e69b8ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5b0aafc603ba02b6702e785b00a5013.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
(2)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
①求实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e05ad029d2bfa4a4349bf78ac90f6803.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5b0aafc603ba02b6702e785b00a5013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
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名校
3 . 若数列
是公差小于零的等差数列,数列
是公比大于零的等比数列,且
,
,
,
.
(1)求数列
和
的通项公式;
(2)设数列
的前n项和为
,求
的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdf53108bee755f5aa9a34ea4d163e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/385275d29d8c8a7841eaeaa3dfab2cdb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a5ab96a5e1963649742b944d420f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49bc99e98cbaa552bf4c138a3bde10e9.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(2)设数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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13-14高三·江苏苏州·阶段练习
解题方法
4 . 设数列{an}满足
.
(1)若a1=3,求证:存在
(a,b,c为常数),使数列{an+f(n)}是等比数列,并求出数列{an}的通项公式;
(2)若an是一个等差数列{bn}的前n项和,求首项a1的值与数列{bn}的通项公式.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7e1283865fa0ec060f5aacfb36d3958.png)
(1)若a1=3,求证:存在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d2d9e07fe79fe89e3646feda7f295d6.png)
(2)若an是一个等差数列{bn}的前n项和,求首项a1的值与数列{bn}的通项公式.
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