香港寵物小精靈村落論壇

標題: Irrational number 被 rationalize 後還是 Irrational number!? [打印本頁]

作者: anthony 時間: 23/7/2005 06:44 PM
標題: Irrational number 被 rationalize 後還是 Irrational number!?
請問如何 rationalize 5/√5?

我把整個數乘以√5/√5，情況如下：
(5/√5)*(√5/√5)
=(5√5)/5
經約簡後等如√5。

√5不是一個 Irrational number 來的嗎？
望高人指點。

作者: JOHNLAM17 時間: 23/7/2005 07:28 PM
只係個分母被rationalise=.=

作者: 抹茶可樂 時間: 23/7/2005 09:27 PM
有理化全稱為「分母有理化」
其實仍然是無理數

作者: anthony 時間: 24/7/2005 06:31 PM

Originally posted by 落雷 at 2005-7-23 09:27 PM:
有理化全稱為「分母有理化」
其實仍然是無理數

那麼是否用"√5"作答案就行了？

作者: JOHNLAM17 時間: 24/7/2005 09:01 PM

Originally posted by anthony at 2005-7-24 06:31 PM:

那麼是否用"√5"作答案就行了？

咁就要睇佢要你咩答案
佢話一d類似"leave the answer in surd form"咁√5就得

作者: 細薯 時間: 24/7/2005 09:31 PM
√2/2 is rational
rational x rational = rational
√2/2 x 2 = √2
therefore √2 is rational
可唔可以咁解.....?

作者: JOHNLAM17 時間: 24/7/2005 11:03 PM

Originally posted by smallpotato226 at 2005-7-24 09:31 PM:
√2/2 is rational
rational x rational = rational
√2/2 x 2 = √2
therefore √2 is rational
可唔可以咁解.....?

√2 is irrational =.=
it cannot be expressed by simple fraction....

作者: 耿鬼孔明 時間: 24/7/2005 11:28 PM

Originally posted by smallpotato226 at 2005-7-24 09:31 PM:
√2/2 is rational
rational x rational = rational
√2/2 x 2 = √2
therefore √2 is rational
可唔可以咁解.....?

√2/2 is not a rational(有理數)
有理數(rational)的定義:
1)整數 e.g:1 2 3
2)有盡小數 e.g:0.5 1.21213483
3)循環小數 e.g:0.11111.... 0.142857142857....
無理數(irrational)的定義
1)無盡小數: e.g:√2 兀
如果你想驗証: 可以按計算機[2][√]看看答案便明了
√2/2 is a irrational
because:√2/2
      =√(2/4)
      =√(1/2)
      =√0.5
so√2/2 is not a rational

作者: 抹茶可樂 時間: 25/7/2005 01:35 AM

Originally posted by anthony at 2005-7-24 06:31 PM:

那麼是否用"√5"作答案就行了？

正確

作者: 細薯 時間: 25/7/2005 02:56 PM
死．．．
我Ｆｏｒｍ２都不如．．．

作者: JOHNLAM17 時間: 25/7/2005 06:09 PM

Originally posted by smallpotato226 at 2005-7-25 02:56 PM:
死．．．
我Ｆｏｒｍ２都不如．．．

你係升form2 or form2....
如果你係form2 o既話...咁就真係死得

作者: 細薯 時間: 25/7/2005 06:49 PM

Originally posted by JOHNLAM17 at 2005-7-25 06:09 PM:

你係升form2 or form2....
如果你係form2 o既話...咁就真係死得

我From 4 la~
(死左lu?!)

作者: JOHNLAM17 時間: 25/7/2005 06:51 PM

Originally posted by smallpotato226 at 2005-7-25 06:49 PM:

我From 4 la~
(死左lu?!)

唔解左你o既意思...sorry
原來你form 4.....
咁就真係有d問題

歡迎光臨香港寵物小精靈村落論壇 (https://proxy.archiver.hkpnve.pokebeacon.com/)

香港寵物小精靈村落 論壇

香港寵物小精靈村落論壇