Irrational number 被 rationalize 後還是 Irrational number!?

anthony

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。

JOHNLAM17

只係個分母被rationalise=.=

抹茶可樂

有理化全稱為「分母有理化」
其實仍然是無理數

anthony

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？

JOHNLAM17

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

細薯

√2/2 is rational
rational x rational = rational
√2/2 x 2 = √2
therefore √2 is rational
可唔可以咁解.....?

JOHNLAM17

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....

耿鬼孔明

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

抹茶可樂

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

細薯

死．．．
我Ｆｏｒｍ２都不如．．．