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#1
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ªèÇÂ͸ԺÒ·ÕèÁҢͧÊÙµÃÊÁ¡ÒáÓÅѧÊͧ ¼ÅºÇ¡¢Í§ÃÒ¡ = -b/a
¢Íú¡Ç¹ªèÇÂ͸ԺÒ·ÕèÁҢͧÊÙµÃ
1. ¼ÅºÇ¡¢Í§ÃÒ¡ÊÁ¡ÒáÓÅѧÊͧ = $\frac{-b}{a}$ ¡Ñº 2. ¼Å¤Ù³¢Í§ÃÒ¡ÊÁ¡ÒáÓÅѧÊͧ = $\frac{c}{a} $ ¢Íº¤Ø³¤èÐ 09 ÊÔ§ËÒ¤Á 2009 13:18 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ gon à˵ؼÅ: Latex |
#2
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ÊÁ¡ÒáÓÅѧÊͧÃÙ»·ÑèÇä» ¤×Í $ax^2 + bx + c = 0$
ËÃ×Í $x^2 + (b/a)x + (c/a) = 0$ ... (1) àÁ×èÍ $a \ne 0$ ÊÁÁµÔÇèÒÃÒ¡¢Í§ÊÁ¡Òôѧ¡ÅèÒǤ×Í $x_1$ ¡Ñº $x_2$ ¨Ðä´éÇèÒÊÁ¡ÒáÓÅѧÊͧ·ÕèÁÕÃÒ¡à»ç¹ $x_1$ ¡Ñº $x_2$ à¢Õ¹ä´éÍաẺã¹ÃÙ»$(x - x_1)(x - x_2) = 0$ ¡ÃШÒÂÍÍ¡ÁÒ¨Ðä´é $x^2 - (x_1+x_2)x + x_1x_2 = 0 $ ...(2) à·ÕºÊÑÁ»ÃÐÊÔ·¸Ôì¢Í§ x ÃÐËÇèÒ§ÊÁ¡Òà (1) ¡Ñº (2) ä´é $-(x_1+x_2) = b/a$ ´Ñ§¹Ñé¹ $x_1 + x_2 = -b/a$ ¡Ñº $x_1x_2 = c/a$ |
#3
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¢Íº¤Ø³¤ÃѺæ à¡çº¢éÍÁÙÅæææ
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