设等差数列
的前
项和为
,若
,
,则
等于
![](https://img.xkw.com/dksih/QBM/2015/3/4/1571990034972672/1571990040494080/STEM/a5e8cf9ada344990af09d335029c5beb.png)
![](https://img.xkw.com/dksih/QBM/2015/3/4/1571990034972672/1571990040494080/STEM/a8f9d28b771d40549c51482e0eb5481b.png)
![](https://img.xkw.com/dksih/QBM/2015/3/4/1571990034972672/1571990040494080/STEM/5a16bde486f947239e1e200ba60b49c1.png)
![](https://img.xkw.com/dksih/QBM/2015/3/4/1571990034972672/1571990040494080/STEM/7a061f45c61b4163baf9257ef4b60ebb.png)
![](https://img.xkw.com/dksih/QBM/2015/3/4/1571990034972672/1571990040494080/STEM/6105393ffce84b379122f60dd0eea15c.png)
![](https://img.xkw.com/dksih/QBM/2015/3/4/1571990034972672/1571990040494080/STEM/217f4e69ef264e2597032cbbf06b27fc.png)
A.![]() | B.![]() | C.![]() | D.![]() |
更新时间:2015-03-04 16:34:24
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