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#1
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ᡵÑÇ»ÃСͺ Kumon 3 ¢éͤÃѺ (ãËÁè)
$1. x^3 + (2a + 1) x^2 + (a^2 + 2a - 1) x + (a^2 - 1)$
$2. ax^2 - a^3 - a^2b + ab^2 + b^3 - bx^2$ $3. (xy - 1) (x - 1) (y + 1) - xy$ ªèÇÂᡵÑÇ»ÃСͺ·Ñé§ÊÒÁ¢éÍàŹФÃѺ áÅÐáÊ´§ÇÔ¸Õ·ÓÍÂèÒ§ÅÐàÍÕ´ |
#2
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ÇÔ¸Õá¡¢éÍ 1 ¹Ð
X3 + (2a+1)X2 +(a2 +2a-1)X + (a2 ?1)
¡è͹Í×è¹á¨¡ X à¢éÒã¹Ç§àÅ纵ÒÁ¹Õé X3 + (2a+1)X2 + X(a2 ?1)+2aX +( a2 ?1) X3 + (2a+1)X2 + (X+1)( a2 ?1) +2aX µèÍä»á¨¡X ǧàÅ纷ÕèàËÅ×Í X3 + 2aX2 + X2 + (X+1)( a2 ?1) +2aX X2 (X+1) + 2aX(X+1) + (X+1)( a2 ?1) (X+1)( X2+2aX+ a2 ?1) (X+1)[ (X+a) 2 ? 1 ] (X+1)(X+a+1)(X+a-1) àÊÃç¨ÊÔ鹤ÃѺ¢éÍ 1 ¢éÍ 2 ¡Ñº 3 à´ëǼÁ¤Ô´µèÍãËé¹Ð¾Í´Õà¨ÍµÍ¹´Ö¡§èǧ
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#3
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¾Í´Õ¼Áãªé LATEX ÂѧäÁèà»ç¹ äÍ X3 ÍèÐ ¤×Í X ¡¡ÓÅѧ 3 ¹Ð
ÍÂèÒ§ a2 ¤×Í a¡¡ÓÅѧ 2 ¹Ð Sorry ¤ÃѺ
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#4
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ÍÂèÒÅ×Á½Ö¡ãªé Latex ¹Ð¤ÃѺ ¤Ø³ Spy Hunter
¢éÍ 2. $(a-b)(x-a-b)(x+a+b)$
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PaTa PatA pAtA Pon! 10 ¾ÄÉÀÒ¤Á 2007 23:07 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ M@gpie |
#5
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ÍéÒ§ÍÔ§:
1. à¢Õ¹ãËÁèä´éà»ç¹ $(x+1)a^2+(2x^2+2x)a+(x+1)(x^2-1)=(x+1)[a^2+2xa+(x-1)(x+1)]$ á¡éÊÁ¡ÒÃËÒ¤èÒ $a$ ¨Ðä´é $a=\dfrac{-2x\pm 2}{2}=-x\pm 1$ ´Ñ§¹Ñé¹ á¡µÑÇ»ÃСͺä´éà»ç¹ $(x+1)(x+a-1)(x+a+1)$ 2. à¢Õ¹ãËÁèä´éà»ç¹ $(a-b)x^2 + (b^3-a^3)+ab(b-a) =(a-b)(x^2-(a+b)^2)$ $=(a-b)(x+a+b)(x-a-b)$ 3. à¢Õ¹ãËÁèä´éà»ç¹ $(y^2+y)x^2-(y^2+3y+1)x+(y+1)$ á¡éÊÁ¡ÒÃËÒ $x$ ¨Ðä´é $x=\dfrac{(y^2+3y+1)\pm\sqrt{(y^2+3y+1)^2-4y(y+1)^2}}{2y(y+1)}$ $=\dfrac{(y^2+3y+1)\pm\sqrt{y^4+2y^3+3y^2+2y+1}}{2y(y+1)}$ $=\dfrac{(y^2+3y+1)\pm\sqrt{(y^2+y+1)^2}}{2y(y+1)}$ $=\dfrac{(y^2+3y+1)\pm(y^2+y+1)}{2y(y+1)}$ $=\dfrac{y+1}{y},\dfrac{1}{y+1}$ ´Ñ§¹Ñé¹á¡µÑÇ»ÃСͺä´éà»ç¹ $y(y+1)\Big(x-\dfrac{y+1}{y}\Big)\Big(x-\dfrac{1}{y+1}\Big)$ $=(xy-y-1)(xy+x-1)$ àÍèÍ ã¤ÃÍÂÒ¡ÅͧàÍÒä»ãªé¡çµÒÁʺÒ¤ÃѺ áµè¼ÁÇèÒ¹Ñ觷ҧ㹹èҨЧèÒ¡ÇèÒ
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site:mathcenter.net ¤Ó¤é¹ |
#6
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¤Ø³ nooonuii ¤ÃѺ ¤×Í¢éÍ·Õè1¡Ñº3 ÁÕÇÔ¸Õ¤Ô´â´ÂäÁèãªéÊÙµÃÁÕäËÁ¤ÃѺ
¤×ÍËÅÑ¡¢Í§¤ØÁͧ 3 ¢é͹ÕéäÁèä´éãËéãªéÊٵùФÃѺ áµèãªéÇԸըѴ¡ÅØèÁä´é¹Ð¤ÃѺ ªèÇÂá¡é䢴éǹФÃѺ |
#7
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ÁÕÍÕ¡¢éͤÃѺ à»ç¹¢éÍ 4 ¹Ð¤ÃѺ
$4. a^2 + 3b^2 + 4ab + 2ac + 6bc - 4b + 4c - 4$ â´ÂàÃÕ§¾¨¹ìµÒÁ¡ÓÅѧ¢Í§ a,b,c (àÅ×Í¡·ÓÍÂèÒ§ã´ÍÂèҧ˹Öè§) ªèǺ͡¾¨¹ì·Õè¨Ð·Ó´éǹФÃѺ ·Ó·Ñé§ 3 ¾¨¹ìàÅÂÂÔ觴դÃѺ ¢Íº¤Ø³¤ÃѺ |
#8
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ÁÒáÅéǤѺ¢éÍ 4
¢ÍºÍ¡¡è͹¹ÐÇèÒãªéä´é⨷Âì ¼Á¤Ô´ËҤӵͺâ´ÂÇÔ¸ÕÊèǹµÑÇ¡è͹Íѹ¹ÕéáÂÂÅÐàÍÕ´¹Ð
(¢ÍÍÀÑÂÍÒ¨ÁÕ¼Ô´¼ÁàºÅͺèͤÃѺ ËØ ËØ ËØ) á¡à¢éÒ¡ÅØèÁµÒÁ¹Õé $(a^2-4)+(2ac+4c)+3b^2+4ab+6bc-4b$ ¨Ðä´é $(a-2)(a+2)+(a+2)(2c)+3b^2+4ab+6bc-4b$ $(a+2)(a-2+2c)+4ab+8b-12b+6bc+3b^2$ $(a+2)(a-2+2c)+4b(a+2)-12b+6bc+3b^2$ $(a+2)(a-2+2c)+b(a+2)+3b(a+2)-12b+6bc+3b^2$ $(a+2)(a-2+2c+b)+3b(a+2)+3b(-4+2c+b)$ $(a+2)(a-2+2c+b)+3b(a+2-4+2c+b)$ $(a+2)(a-2+2c+b)+3b(a-2+2c+b)$ $(a+3b+2)(a+b+2c-2)$ ¨ºáÅéǤÃѺâËà˹×èÍÂáÎÐ ËÇѧÇèÒ¤§ÅÐàÍÕ´¾Í¹Ð¤ÃѺ
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¡Ò÷Ó⨷ÂìàËÁ×͹·Ó¡Ñº¢éÒÇ äÁè½Ö¡ äÁè·Ó¡çäÁèÁÕÇѹà»ç¹ |
#9
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ÍéÒ§ÍÔ§:
¢éÍ 1. ÊÁÁµÔãËé $x^3 + (2a + 1) x^2 + (a^2 + 2a - 1) x + (a^2 - 1)=(x+k_1)(x+k_2)(x+k_3)$ à·ÕºÊÑÁ»ÃÐÊÔ·¸Ôì ¨Ðä´é $$\begin{array}{rcl} k_1+k_2+k_3&=&2a+1\\ k_1k_2+k_2k_3+k_3k_1&=&a^2+2a-1\\ k_1k_2k_3&=&a^2-1\\ \end{array}$$ (ÊѧࡵºÃ÷Ѵáá¤×Í¹Ó $k$ ÁÒ·ÕÅÐ 1 µÑÇ ºÃ÷ѴµèÍÁÒ¡ç¤×Í·ÕÅÐ 2 áÅÐ 3 µÑǵÒÁÅӴѺ) â´Â¡ÒÃÊѧࡵ¨Ò¡ÊÁ¡ÒÃÊØ´·éÒ (´ÙÇèÒÍÐääٳ¡Ñ¹áÅéÇä´é $a^2-1$) ¨Ðä´é $(k_1,k_2,k_3)=(1,a+1,a-1)$ (ÊÅѺ·Õè¡Ñ¹ä´é) áÅÐàÁ×è͹Ó仵ÃǨÊͺ¡ÑºÊͧÊÁ¡Ò÷ÕèàËÅ×Í ¾ºÇèÒÊÁ¡ÒÃà»ç¹¨ÃÔ§ ©Ð¹Ñé¹ $x^3 + (2a + 1) x^2 + (a^2 + 2a - 1) x + (a^2 - 1)=(x+1)(x+a+1)(x+a-1)$ Êèǹ¢éÍ 3. ¾Ô¨ÒÃ³Ò $(xy-1)(x-1)(y+1)-xy=(xy-1)(xy+(x-y-1))-xy$ á·¹·Õè¨ÐÁͧã¹ÃÙ»¾ËعÒÁµÑÇá»Ã $x$ àËÁ×͹¢éÍ 1. ãËéÁͧãËéÃÙ»¢Í§¾ËعÒÁ $xy$ â´ÂãËé $xy=z$ ©Ð¹Ñé¹ $$\begin{array}{rcl} (xy-1)(x-1)(y+1)-xy&=&(z-1)(z+(x-y-1))-xy\\ &=&z^2+(x-y-2)z-(xy+x-y-1)\\ &=&z^2+(x-y-2)z-(x-1)(y+1)\\ &=&z^2+(x-y-2)z+(x-1)(-y-1)\\ &=&(z+x-1)(z-y-1)\\ &=&(xy+x-1)(xy-y-1) \end{array}$$ ã¹·Õè¹Õéá·¹ $xy=z$ à¾×èÍäÁèãËé¾ËعÒÁ´Ù«Ñº«é͹¨¹µÒÅÒ¤ÃѺ áÅÐÊѧࡵÇèÒàÃÒäÁèá·¹ $xy$ ¾¨¹ìÊØ´·éÒ à¾×èÍãË龨¹ì·éÒ æ ÊÒÁÒöà¢Õ¹à»ç¹¼Å¤Ù³ä´é¤ÃѺ 11 ¾ÄÉÀÒ¤Á 2007 21:39 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ Mathophile |
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ËÑÇ¢éÍ | ¼ÙéµÑé§ËÑÇ¢éÍ | Ëéͧ | ¤ÓµÍº | ¢éͤÇÒÁÅèÒÊØ´ |
ᡵÑÇ»ÃСͺ Kumon | first | »ÑËÒ¤³ÔµÈÒʵÃì Á. µé¹ | 2 | 10 ¾ÄÉÀÒ¤Á 2007 17:21 |
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