陈向东代数题75题求解

jaffa23

Are there exactly 3 distinct symbols used to create the code words in language Q?
1.The set of all code words in language Q is the set of all possible distinct horizontal arrangement of one or more symbols,with no repetition.
2.There are exactly 15 code words in language Q.

答案为C。说实话，我压根理解不了。。。。

arthurman

If there are 3 distinct symbols, we can arrange one or more of them on the

line without repetition:
1 symbol only: 3 possibilities.
2 symbols: 3*2= 6 possibilities.
3 symbols: 3*2=6 possibilites

Total possibilities = 15. 15 distint words reprented by 3 distinct symbols.

Bingo.

CCCC

mudiduanger

我是没看懂ls的解释，不过条件1+2就=问题了。。。  果断c

yidiyuehans

同意2楼。多读几遍题就没问题了

jaffa23

谢谢楼上各位