有條唔識,
8 letters marked A,B,C,D,E,F,G,H
When the letters are placed in a row ,find the number is arrangements if the letters A,B,C,Dare separated from each other.
Math&Stat 有條唔識
2009-10-19 10:13 pm
回答 (4)
2009-10-20 5:49 am
2009-10-21 1:56 am
2009-10-20 12:12 am
A, B, C, D separated from each other
Possible arrangement:
(1) A_B_C_D_ or
(2) _A_B_C_D
(_is for E, F, G, H)
No. of arrangements
= 4! x 4! x 2
= 1152
[第一個4!係for A, B, C, D, 另一個4!係for E, F, G, H, x2因為有(1)同(2)兩個不同排列]
Possible arrangement:
(1) A_B_C_D_ or
(2) _A_B_C_D
(_is for E, F, G, H)
No. of arrangements
= 4! x 4! x 2
= 1152
[第一個4!係for A, B, C, D, 另一個4!係for E, F, G, H, x2因為有(1)同(2)兩個不同排列]
2009-10-19 10:22 pm
_
將8letters排列方法減走abcd一齊既排列方法就行
排列方法
=8!-(4!)(5!)或8!-(4!)(4!)(5)
=37440
將8letters排列方法減走abcd一齊既排列方法就行
排列方法
=8!-(4!)(5!)或8!-(4!)(4!)(5)
=37440
收錄日期: 2021-04-23 23:21:57
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