1 . 已知等比数列
的公比
,其n前项和为![](https://img.xkw.com/dksih/QBM/2016/1/5/1572415331491840/1572415336792064/STEM/e5ae5b8d86a04ad1b1d4ddcd323f7900.png)
(Ⅰ)求公比q和a5的值;
(Ⅱ)求证:
![](https://img.xkw.com/dksih/QBM/2016/1/5/1572415331491840/1572415336792064/STEM/87f4893108f248a8982db026c71893d1.png)
![](https://img.xkw.com/dksih/QBM/2016/1/5/1572415331491840/1572415336792064/STEM/a2272c5ae1724237964d50c051e7258d.png)
![](https://img.xkw.com/dksih/QBM/2016/1/5/1572415331491840/1572415336792064/STEM/e5ae5b8d86a04ad1b1d4ddcd323f7900.png)
(Ⅰ)求公比q和a5的值;
(Ⅱ)求证:
![](https://img.xkw.com/dksih/QBM/2016/1/5/1572415331491840/1572415336792064/STEM/2b2cc53aedb84695a5ca168d423a76cb.png)
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2 . 已知数列
的前
项和
.
(Ⅰ)求
的值;
(Ⅱ)求证:
;
(Ⅲ)判断数列
是否为等差数列,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d737c1047a14cee12a6671383e244fa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/26c147d47e48bc5ceb2ae64ffa7ac9d5.png)
(Ⅰ)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
(Ⅱ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87985276923c0777cb6f5a07a316668e.png)
(Ⅲ)判断数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d737c1047a14cee12a6671383e244fa5.png)
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3 . 在△ABC中,角A,B,C的对边分别为a ,b,c.若 c=4,
则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380bbacf854e30e2e747fc286d2b9997.png)
__________ ,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6748e4496d0b9cd32b8286f42b42be0a.png)
__________ .
![](https://img.xkw.com/dksih/QBM/2016/1/5/1572415331491840/1572415336677376/STEM/87a242d53a74489196bf1dac59d4bff1.png?resizew=176)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380bbacf854e30e2e747fc286d2b9997.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6748e4496d0b9cd32b8286f42b42be0a.png)
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4 . 在
中,若![](https://img.xkw.com/dksih/QBM/2015/4/22/1572079748554752/1572079754371072/STEM/a32c37c0867341a3aec1d1c351d87964.png?resizew=252)
_________ .
![](https://img.xkw.com/dksih/QBM/2015/4/22/1572079748554752/1572079754371072/STEM/19188b2cc17f426495a206a8a715c1a4.png?resizew=45)
![](https://img.xkw.com/dksih/QBM/2015/4/22/1572079748554752/1572079754371072/STEM/a32c37c0867341a3aec1d1c351d87964.png?resizew=252)
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5 . 若等差数列
满足
,
,则
= ______.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f482800582e90435b5da37ad530650a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a01677d192d3f01833bc38bc01ec8621.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d611dfb7c33b9f5e52e839997f66eb76.png)
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6 . 在
中,若
,则
的大小为_______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fdda62f728adfdf1e01abcca65d4f930.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/febc9a89d0d1c97b88c0f4acd32b4e67.png)
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