→ bestforyou:分項對消? 03/28 17:13
推 lyricslee:+=啥意思~是加到底嗎? 03/28 17:50
→ lyricslee:不然硬算就好了 03/28 17:51
推 lyricslee:硬要漂亮解...似乎是分母可以拆成1/3*n(n+1)(n+2) 03/28 17:57
推 jashbala:樓上是n(n+1)(n+2)/3 03/28 18:04
→ jashbala:分母是n(n+1)(n+2)/3 03/28 18:04
推 lyricslee:恩我知道~1/3抱歉沒括號 03/28 19:13
→ iancc:+=是我打錯了 不好意思, 謝謝各位!!! 03/28 22:11