Discuz Math Forum»Forum › Mathematics › High School › 数列

Return to list New

View 1607|Reply 2

[数列] 数列

[Copy link]

168 Threads	383 Posts	3329 Credits

Credits: 3329

Send PM

lrh2006 Posted 2017-6-4 11:07 |Read mode

请各位指点下，怎么做比较好，为什么可以把Sn看成n2?谢谢！ QQ图片20170604110452.png

QQ图片20170604110452.png

Reply Edit

277 Threads	547 Posts	5413 Credits

Credits: 5413

Send PM

力工 Posted 2017-6-4 15:30

回复 1# lrh2006

直接用和的性质：等比，和为关于$q^n$的二项形式，那个什么系数与常数项和为$0$.就成关于$n$的恒等式了。

Reply Edit

168 Threads	383 Posts	3329 Credits

Credits: 3329

Send PM

Author| lrh2006 Posted 2017-6-6 10:06

回复 2# 力工

好的，谢谢

Reply Edit

Return to list New

Mobile version|Discuz Math Forum

2025-5-31 10:52 GMT+8

Powered by Discuz!

× Quick Reply To Top Edit