#1
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͹ءÃÁ¤èÐ
¼ÅºÇ¡ n ¾¨¹ìáá¢Í§ÅӴѺàÅ¢¤³ÔµÊͧÅӴѺà»ç¹ 7n+2:n+4 ÍѵÃÒÊèǹ¢Í§¾¨¹ì·Õè 5 ¢Í§ÊͧÅӴѺ¹Õéà»ç¹à·èÒã´
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#2
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ãËé $a_1,b_1$ à»ç¹ ¾¨¹ìááÊØ´¢Í§ sequence áá¡Ñº·Õè 2 µÒÁÅӴѺ áÅÐ $c,d$ à»ç¹ common difference (ÀÒÉÒä·ÂàÃÕ¡ÇèÒÍÐääÃѺ ªèǺ͡·Õ...) ¢Í§ sequence áá¡Ñº·Õè 2 µÒÁÅӴѺ
$\therefore\frac{\frac{2a_1+(n-1)c}{2}}{\frac{2b_1+(n-1)d}{2}}=\frac{7n+2}{n+4}$ $\frac{2a_1+(n-1)c}{2b_2+(n-1)d}=\frac{7n+2}{n+4}$ ãËé $n=9$ ä´éÇèÒ $\frac{2a_1+8c}{2b_1+8d}=\frac{65}{13}$ $\therefore\frac{a_1+4c}{b_1+4d}=\frac{a_5}{b_5}=5$ 17 ¾ÄÉÀÒ¤Á 2008 20:08 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ owlpenguin |
#3
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common difference ¤×Í ¼ÅµèÒ§ÃèÇÁ¤ÃѺ
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¤¹ä·ÂÃèÇÁã¨ÍÂèÒãªéÀÒÉÒÇÔºÑµÔ ½Ö¡¾ÔÁ¾ìÊÑÅѡɳìÊÑ¡¹Ô´ ªÕÇÔµ(¤¹µÍºáÅФ¹¶ÒÁ)¨Ð§èÒ¢Öé¹àÂÍÐ (¨ÃÔ§æ¹Ð) Stay Hungry. Stay Foolish. |
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