解题方法
1 . 记
为等差数列
的前n项和,已知
,
,
,
的前n项和为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681967bfbdcdae96320e06da896b4da4.png)
_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ac577f987d768e1a115f2747ec0fd6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3977c8261a26b09c1aa8d1ff87075666.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9ebf05ca12f9da810b2b10e066ececf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/681967bfbdcdae96320e06da896b4da4.png)
您最近一年使用:0次
2 . 给出下列命题:①等比数列1,
,
,
,…(
)的前
项和为
;②等差数列
中,若
,
,则该数列的前13项或14项之和最大;③若等差数列
公差为
,则其前
项和
;④若等比数列
单调递增的充要条件是首项
,且公比
;⑤若数列
满足
,
,则
.其中正确的是______ (把你认为正确的命题序号都填上).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8cc0b4997cae4d8aec791a1d3923314.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87b367f647833446cf684c3ddedb1592.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20849c00c47cbdc43f18d53341b6c4e5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cef311c39ffa93698337da80bb551d3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c339234052548a53ce660908f38a1210.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/112896d1e2bca1811d0e4584db40906c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2efd3ae9ca4a2f807b476f09bc7d135b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/390636a89883bd64bf8da9bf8654aff9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eda6dc559d07bc22c9a0ed1e3a6d01d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c5dca4e85b2473ebe529b897e7c4086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97034664bd213a31e81b9625f83d0e26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c700b3d474933d7a0c68275e03844474.png)
您最近一年使用:0次