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à¤Ã×èͧÁ×ͧ͢ËÑÇ¢éÍ | ¤é¹ËÒã¹ËÑÇ¢é͹Õé |
#1
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⨷Â줳Ե Á.3¤ÃѺ ªèÇÂ˹èͤÃѺ
¢Íá¹Ç¤Ô´Ë¹èͤÃѺ
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#2
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..,,.,,.......
10 ÁÕ¹Ò¤Á 2015 11:33 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 2 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ boat25451 |
#3
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¢éÍ 10
$a^2(1+a)=n^2$ áÊ´§ÇèÒ a+1 µéͧà»ç¹¡ÓÅѧÊͧÊÁºÙÃ³ì ·ÕèÁÕ¤èÒµÑé§áµè 2 ¨¹¶Ö§ 101 ä´éá¡è 4,9,16,25,36,49,64,81,100 ´Ñ§¹Ñé¹ ¤èҢͧ a ä´éá¡è 3,8,15,24,35,48,63,80,99 ÁÕ¤èÒ a ÍÂÙè 9 µÑÇ |
#4
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¢éÍ 3
âÍ¡ÒÊËÂÔºÅÙ¡ÊÕá´§ = 1/5 âÍ¡ÒÊËÂÔºÅÙ¡ÊÕà¢ÕÂÇ = 3/5 âÍ¡ÒÊËÂÔºä´éÅÙ¡¢ÒÇ = 1-(1/5)-(3/5) =1/5 ä´éÇèÒºÍÅá´§=ºÍÅ¢ÒÇ=7 ÅÙ¡ ºÍÅà¢ÕÂÇ=3(ºÍÅ¢ÒÇ)=3(7)=21 ÅÙ¡ x=7,y=21 |
#5
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¢éÍ 2 äÁèÁÕâ»Ãá¡ÃÁÇÒ´ÃÙ» àÅ¢ÍäÁè͸ԺÒ Ãͤ¹Í×è¹Í¸ÔºÒÂÅСѹ¤ÃѺ
µÍº (1/3*15*15*36)-(1/3*10*10*24)=2700-800=1900 ź.«Á. |
#6
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¢éÍ 1
á¡éÊÁ¡ÒøÃÃÁ´Ò¨¹à»ç¹ $\frac{1}{x-1} -1=\frac{x}{x+1} $ $\frac{2-x}{x-1} =\frac{x}{x+1} $ $(2-x)(x+1)=x(x-1)$ $-x^2+x+2=x^2-x$ $2x^2-2x-2=0$ $x^2-x-1=0$ $x=\frac{1\pm \sqrt{5} }{2} $ a ÁÒ¡¡ÇèÒ 0 $a=\frac{1+ \sqrt{5} }{2} =1.618$ a ã¡Åéà¤Õ§ 2 ·ÕèÊØ´ |
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