markfang2050 发表于 2019-10-28 20:25:14

求无穷级数之和

求无穷级数之和

zeroieme 发表于 2019-10-28 20:40:44

\(\frac{\pi ^4}{90}\)

zeroieme 发表于 2019-10-29 06:17:23

https://wenku.baidu.com/view/9ad6445848d7c1c708a145f4.html
http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=gdhsxb-zrkxb200806015
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