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͹ءÃÁáÅÐÊÁ¡ÒäÃѺ
1.¨§áÊ´§ÇèÒ$\frac{x^{9999}+x^{8888}+x^{7777}+x^{6666}+x^{5555}+x^{4444}+x^{3333}+x^{2222}+x^{1111}+1}{x^9+x^8+x^7+........+x+1}$ à»ç¹¨Ó¹Ç¹àµçÁ
2.¨§ËÒ¤èҢͧ $\frac{(1^4+\frac{1}{4} )(3^4+\frac{1}{4} ).............((2n-1)^4+\frac{1}{4}) }{(2^4+\frac{1}{4} )(4^4+\frac{1}{4} ).............((2n)^4+\frac{1}{4}) }$
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ÊÑÁËÃѺ¤³ÔµÈÒʵÃì ¼ÁäÁèÁÕáÁé«Ö觾ÃÊÇÃäìäÁèÁÕáÁéâÍ¡ÒÊ´éÇÂÍÂØèµèÒ§¨Ñ§ËÇÑ´ ¨ÐÁÕ¡çáµè¤ÇÒÁÃÑ¡·Õè·ØèÁà·.... |
#2
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2. $x^4+4y^4=(x^2-2xy+2y^2)(x^2+2xy+2y^2)$.
$y=\dfrac{1}{2}$
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site:mathcenter.net ¤Ó¤é¹ 23 ¡Ã¡®Ò¤Á 2009 18:41 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ nooonuii |
#3
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ÊÓËÃѺ¢éÍ 1 ¹Ð¤Ñº
¡Ó˹´ãËé $ K= \frac{x^{1111}-1}{x-1} = x^{1110}+x^{1109}+...+x+1 ,$ $a = x^{9999}+x^{8888}+x^{7777}+...+x^{1111}+1 $ áÅÐ $b = x^9+x^8+x^7+...+x+1 $ µéͧ¡ÒÃáÊ´§ÇèÒ $ \frac{a}{b}$à»ç¹¨Ó¹Ç¹àµçÁ ¡è͹Í×è¹Åͧ¾Ô¨ÒÃ³Ò $\frac {aK}{b}= \frac{(x^{9999}+x^{8888}+x^{7777}+...+x^{1111}+1)(x^{1111}-1)}{(x^9+x^8+x^7+...+x+1)(x-1)}$ $= \frac{x^{11110}-1}{x^{10}-1}$ «Öè§à¹×èͧ¨Ò¡ $(x^{10}-1) | (x^{11110}-1)$ ´Ñ§¹Ñé¹ $\frac {aK}{b}$à»ç¹¨Ó¹Ç¹àµçÁ ¶éÒàÃÒáÊ´§ä´éÇèÒ $gcd(K,b)=1$ (ã¹·Õè¹Õé $gcd(K,b)$ á·¹µÑÇËÒÃÃèÇÁÁÒ¡¢Í§ K,b) àÃÒ¡ç¨Ðä´éÇèÒ $b | a$ ¨Ò¡ $ K= x^{1110}+x^{1109}+...+x+1 ,b = x^9+x^8+x^7+...+x+1$ ÊÒÁÒöãªé¡ÒõÑé§ËÒøÃÃÁ´Òà¾×èÍáÊ´§ÇèÒ $gcd(K,b)=1$ ´Ñ§¹Ñé¹ àÃÒ¨Ö§ä´éÇèÒ $b | a$ ¹Ñ蹤×Í $\frac{a}{b}$ à»ç¹¨Ó¹Ç¹àµçÁ ÊÓËÃѺ·èÒ¹·Õèµéͧ¡ÒÃàªç¤¤ÓµÍº¢éÍ 2 ¤ÓµÍº¤×Í $\frac{1}{8n^2+4n+1}$ ¤Ñº |
#4
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¢éÍ 1 ¤Ù³ (x-1) º¹ÅèÒ§áÅéÇÂÑ´àÈÉàËÅ×Í¡ç¹èÒ¨Ðä´é¤ÃѺ
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