新GRE数学要点:Set

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Set 　　A set is a collection of objects or things. Each object in a set a member or element of that set.Size of a set is the number of members in the set.
　　Example:
+ \: |6 z: J# N2 ^0 I! E　　The set of even numbers between 2 and 10 is of size 5:{2,4,6,8,10}.
　　The set of primes between 2 and 10 is of size 4:{2,3,5,7}.
) \7 F4 Z, ^; e" {8 z8 |5 ~　　Remember:
$ B. W$ i1 n$ [6 ~% T: t% c7 w' d　　Each member of set A belongs to A or is in the set A.
, L2 W9 Y0 }$ I; @　　A set can not have repeating member:{1,3,1,2}is not a set.
　　Rearranging the order of the members does not change the set:{1,2,3}is same as{3,2,1}.