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#1
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͹ءÃÁ¤ÃѺ ªèÇÂ˹è͹ФÃѺ ...
1.¨§ËҼźǡ n ¾¨¹ìáá¢Í§Í¹Ø¡ÃÁ $8+88+888+8888+\underbrace{888...888}_{n} +...$
2.¨§ËҼźǡ n ¾¨¹ìáá¢Í§Í¹Ø¡ÃÁ $\frac{\sqrt{2}-1}{1\bullet \sqrt{2} }+\frac{\sqrt{3}-\sqrt{2} }{\sqrt{2}\bullet \sqrt{3}} + \frac{2-\sqrt{3} }{\sqrt{3}\bullet 2 } +...+\frac{\sqrt{n+1}-\sqrt{n} }{\sqrt{n}\sqrt{n+1}+... } $ 3.$\frac{4}{1\bullet 3\bullet 5} + \frac{4}{3\bullet 5\bullet 7}+\frac{4}{5\bullet 7\bullet 9}+...+\frac{4}{(2n-1)(2n+1)(2n+3)} + .... $ ¼Á·ÓäÁèä´éÍèÒ¤ÃѺT_T
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#2
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¢éÍ 1 ÅͧËÒ¤èҢͧ $9+99+999+999...9$ ¡è͹¤ÃѺ (â´Â¾¨¹ìÊØ´·éÒÂÁÕ $9$ ÍÂÙè $n$ µÑÇ)
¢éÍ 2 Åͧá¡àÈÉà»ç¹¾¨¹ìà´ÕÂÇ´Ù¡è͹¤ÃѺ ¢éÍ 3 ¹ÕèÅͧ´Ù¡ÒèѴÃÙ»¾¨¹ì·Õè¤ÃѺ $$\frac{1}{1\cdot3\cdot5}=\frac{1}{4}[\frac{1}{1\cdot3}-\frac{1}{3\cdot5}]$$ |
#3
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¢éÍÍ×è¹à¢éÒã¨ËÁ´áÅéǤÃѺ ¢Íº¤Ø³¤ÃѺ
áµèÇèÒ¢éÍ2 ÍèÒ¤ÃѺ á¡àÈÉÂѧä§ÍèÒ¤ÃѺ äÁèà¢éÒ㨠= =''
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#4
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#3
á¡àÈÉÍÍ¡ÁÒ·ÕÅеÑÇàŤÃѺ |
#5
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$\frac{\sqrt{2}-1}{1\cdot\sqrt{2}}=\frac{\sqrt{2}}{1\cdot\sqrt{2}}-\frac{1}{1\cdot\sqrt{2}}=1-\frac{1}{\sqrt{2}}$
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¤³ÔµÈÒʵÃì ¤×Í ÀÒÉÒÊÒ¡Å ¤³ÔµÈÒʵÃì ¤×Í ¤ÇÒÁÊǧÒÁ ¤³ÔµÈÒʵÃì ¤×Í ¤ÇÒÁ¨ÃÔ§ µÔ´µÒÁªÁ¤ÅÔ»ÇÕ´ÕâÍä´é·Õèhttp://www.youtube.com/user/poperKM |
#6
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ÍëÍ à¢éÒã¨áÅéǤÃѺ ¢Íº¤Ø³¤ÃѺ
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