|
|
#2
16 ¡ØÁÀҾѹ¸ì 2010, 13:05
|
|||
|
|||
ÍéÒ§ÍÔ§:
$(-25^{\frac{1}{2}})^2 \not = \ ?? $ ¤ÃѺ  ẺÇèÒ $ \ (-a)^2 = (-a)(-a) = a^2 \ $ ËÃ×Í $(-2)(-2) = 4 $ ´Ñ§¹Ñé¹ $ \ (-25^{\frac{1}{2}})^2 = (-25^{\frac{1}{2}})(-25^{\frac{1}{2}}) = 25$ ËÁÒÂà赯 $ \ - (25^{\frac{1}{2}})^2 = - 25 $
__________________
ÁÒËÒ¤ÇÒÁÃÙéäÇéµÔÇËÅÒ¹ áµèËÅÒ¹äÁèàÍÒàÅ¢áÅéÇ à¢éÒÁÒ·ÓàÅ¢àÍÒÁѹÍÂèÒ§à´ÕÂÇ  ¤ÇÒÁÃÙéà»ç¹ÊÔè§à´ÕÂÇ·ÕèÂÔè§ãËé ÂÔè§ÁÕÁÒ¡ ÃÙéÍÐäÃäÁèÊÙé ÃÙé¨Ñ¡¾Í (¡àÇ鹤ÇÒÁÃÙé äÁèµéͧ¾Í¡çä´é ËÒäÇéÁÒ¡æáËÅдÕ) (áµè¡çÍÂèÒãËéÁÒ¡¨¹·èÇÁËÑÇ àÍÒµÑÇäÁèÃÍ´)
|
|
#4
16 ¡ØÁÀҾѹ¸ì 2010, 14:09
|
|||
|
|||
|
ÍéÒ§ÍÔ§:
¼ÁäÁèªÍºãªé¡ÓÅѧ ËÃ×ͶéÒ¨ÐÁͧã¹ÃÙ»¢Í§ÃÒ¡ $(-25^{\frac{1}{2}})$ ¡ç¤×Í $-\sqrt{25} = (-1) (\sqrt{25})$ $(-25^{\frac{1}{2}})^2= (-\sqrt{25})(-\sqrt{25}) = (-1)(\sqrt{25})(-1)(\sqrt{25}) = 25 $ ä˹æ¡çä˹áÅéÇ µÒÁ¤ÓÃéͧ¢Í Åͧãªé¡ÓÅѧ´Ù¡çä´é¤ÃѺ $(-25^{\frac{1}{2}})^2 = [(-1)(25^{\frac{1}{2}})]^2 = (-1)^2(25^{\frac{1}{2}})^2 = (1)(25^{\frac{2}{2}}) = (1)(25) = 25$
__________________
ÁÒËÒ¤ÇÒÁÃÙéäÇéµÔÇËÅÒ¹ áµèËÅÒ¹äÁèàÍÒàÅ¢áÅéÇ à¢éÒÁÒ·ÓàÅ¢àÍÒÁѹÍÂèÒ§à´ÕÂÇ ¤ÇÒÁÃÙéà»ç¹ÊÔè§à´ÕÂÇ·ÕèÂÔè§ãËé ÂÔè§ÁÕÁÒ¡ ÃÙéÍÐäÃäÁèÊÙé ÃÙé¨Ñ¡¾Í (¡àÇ鹤ÇÒÁÃÙé äÁèµéͧ¾Í¡çä´é ËÒäÇéÁÒ¡æáËÅдÕ) (áµè¡çÍÂèÒãËéÁÒ¡¨¹·èÇÁËÑÇ àÍÒµÑÇäÁèÃÍ´)
16 ¡ØÁÀҾѹ¸ì 2010 15:33 : ¢éͤÇÒÁ¹Õé¶Ù¡á¡éä¢áÅéÇ 1 ¤ÃÑé§, ¤ÃÑé§ÅèÒÊØ´â´Â¤Ø³ banker
|
  |
|
|
