1 . 等比数列的性质
已知
为等比数列,公比为
,
为其前
项和.
(1)若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8647b84bfbc7d827f56be74888b9fdb6.png)
______ ;
(2)当
时,
,________ ,
为等比数列;
(3)若等比数列
共
项,记
为诸奇数项和,
为诸偶数项和,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/186fad5c3b123434e46e02c26dcc3c32.png)
____ ;
已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c618d7069d2e18c8164ed0e6fa7811f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8647b84bfbc7d827f56be74888b9fdb6.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1d236a265a6cc0f3d06a0e568ffa907.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7ce01c8a13621ad26ea353b067dfaa8.png)
(3)若等比数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5631bc01b998a4b3fabd9e131699dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9df956d8d43778655131703be9ad9a41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16ce99d82b6ad34142c6920031a454e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/186fad5c3b123434e46e02c26dcc3c32.png)
您最近一年使用:0次
名校
2 . 下列叙述中,
①等差数列
,
为其前n项和,若
,
,则当
时,
最小;
②等差数列
的公差为d,前n项和为
,若
,则
为递增数列;
③等比数列
的前n项和为
,若
,则
有最小项;
④在等差数列
中,记
,若存在
,使得
,则
为递增数列.
正确说法有______ (写出所有正确说法的序号)
①等差数列
![](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/b134439819d3069da709979cb9b1a991.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5846713aaecbab35ad985cbe9ad7d44a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd6cd3173d146902c5518503888c3b59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
②等差数列
![](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/c4ce64685821c3e55c07f151996ca8c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/846fa57d92d6ad44d6a0cafad1e71ed4.png)
③等比数列
![](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/ba5c8a6c196890aa7871ea0c82061ea5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/846fa57d92d6ad44d6a0cafad1e71ed4.png)
④在等差数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134aefab10d3e81e223e9123da5f417e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f29c06a3e9a73e905eb87d71efa201c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbb50854126e66c09294192ed1db29ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
正确说法有
您最近一年使用:0次