### + / -檢視主題

(9n+1)^3同餘1(mod 9)
(9n+2)^3同餘-1(mod 9)
(9n+3)^3同餘0(mod 9)
(9n+4)^3同餘1(mod 9)
(9n+5)^3同餘-1(mod 9)
(9n+6)^3同餘0(mod 9)
(9n+7)^3同餘1(mod 9)
(9n+8)^3同餘-1(mod 9)

is 寫到:#ed_op#div#ed_cl#那麼#ed_op#/div#ed_cl##ed_op#div#ed_cl#4=(&nbsp; )#ed_op#sup#ed_cl#3#ed_op#/sup#ed_cl#+(&nbsp; )#ed_op#sup#ed_cl#3#ed_op#/sup#ed_cl#+(&nbsp; )#ed_op#sup#ed_cl#3#ed_op#/sup#ed_cl##ed_op#/div#ed_cl##ed_op#div#ed_cl##ed_op#sup#ed_cl#我怎麼都想不到...#ed_op#img src="/phpBB2/richedit/smileys/aa104.gif"#ed_cl##ed_op#/sup#ed_cl##ed_op#/div#ed_cl#
#ed_op#br#ed_cl#對，5也是一個反例...#ed_op#br#ed_cl#5=(&nbsp; )#ed_op#sup#ed_cl#3#ed_op#/sup#ed_cl#+(&nbsp; )#ed_op#sup#ed_cl#3#ed_op#/sup#ed_cl#+(&nbsp; )#ed_op#sup#ed_cl#3#ed_op#/sup#ed_cl##ed_op#br#ed_cl#??
#ed_op#DIV#ed_cl#那麼#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#4=(&nbsp; )#ed_op#SUP#ed_cl#3#ed_op#/SUP#ed_cl#+(&nbsp; )#ed_op#SUP#ed_cl#3#ed_op#/SUP#ed_cl#+(&nbsp; )#ed_op#SUP#ed_cl#3#ed_op#/SUP#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#SUP#ed_cl#我怎麼都想不到...#ed_op#IMG src="/phpBB2/richedit/smileys/aa104.gif"#ed_cl##ed_op#/SUP#ed_cl##ed_op#/DIV#ed_cl#

### [問題]你的問題

#ed_op#DIV#ed_cl#是我說得不清楚....舉個例子:#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#&nbsp;#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#(-2)^3+1^3+1^3=-6#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#(-1)^3+0^3+0^3=-1#ed_op#/DIV#ed_cl#

### Re: [問題]立方數和

tangpakchiu 寫到:#ed_op#div#ed_cl#試證或反證任何一個整數都可表示成三個立方數之和。#ed_op#/div#ed_cl##ed_op#div#ed_cl##ed_op#/div#ed_cl#
#ed_op#br#ed_cl#該是任何#ed_op#span style="font-weight: bold;"#ed_cl#正#ed_op#/span#ed_cl#整數嗎？有必要大於2嗎？#ed_op#br#ed_cl#4=1+1+2，而2不是立方數吧~~#ed_op#br#ed_cl##ed_op#br#ed_cl##ed_op#br#ed_cl#

### [問題]立方數和

#ed_op#DIV#ed_cl#試證或反證任何一個整數都可表示成三個立方數之和。#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl#