2016年新GRE数学考试重要考点知识小结.doc

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2016年新GRE数学考试重要考点知识小结

（1）
Set
A set is a collection of objects or things. Each object i 第1页 /总页数 2 页
2016年新GRE数学考试重要考点知识小结

（1）
Set
A set is a collection of objects or things. Each object in a set a member or element of that of a set is the number of members in the set.
Example:
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}.
Remember:
Each member of set A belongs to A or is in the set A.
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}.
Combinations
Number of ways we can select n objects from a group of m distinct objects is m!/(n!*(mn)!)
（2）
Example:
Number of possible ways to pick 4 oscar nominations from a list of 50 movies is 50!/(4!*(504)!)=50!/(4!*46!)=50*49*48*47/24=230300.