新gre数学考点介绍：set、排列、组合
新gre考试实施以来，不仅对写作部分茫然不知所措，就连我们所擅长的数学也甚是担忧，相信这其中的原因还是由于考生在新gre数学复习时没有把基础打牢。如果新版gre数学基本考点都没有复习到，如何能拿到分数呢?所以说，想要新版gre数学考好，复习的时候一定要把基本概念和重要考点都弄扎实。
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:
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!/!).
Example:
Number of possible ways to pick 4 oscar nominations from a list of 50 movies is 50!/!)=50!/=50494847/24=230300.
Remember:
This does not apply if there are identical objects.
Permutation of Objects
The number of ways n distinct objects can be ordered is n!.
Example:
Number of ways 6 people can from a queue is 6!.
Number of ways 5 different cars can be parked in 5 parking spaces is 5!.
Remember:
This does not apply if there are identical objects or ordering does not matter.
由于美国数学基础教育的难度增加导致数学考试越来越难，但新gre数学复习考点都是高中时候学到的知识点，考生不要过于紧张，把基本概念弄明白，再记住一些新版gre数学必备的词汇，那么相信新版gre数学应该没有问题。
新gre考试实施以来，不仅对写作部分茫然不知所措，就连我们所擅长的数学也甚是担忧，相信这其中的原因还是由于考生在新gre数学复习时没有把基础打牢。如果新版gre数学基本考点都没有复习到，如何能拿到分数呢?所以说，想要新版gre数学考好，复习的时候一定要把基本概念和重要考点都弄扎实。
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:
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!/!).
Example:
Number of possible ways to pick 4 oscar nominations from a list of 50 movies is 50!/!)=50!/=50494847/24=230300.
Remember:
This does not apply if there are identical objects.
Permutation of Objects
The number of ways n distinct objects can be ordered is n!.
Example:
Number of ways 6 people can from a queue is 6!.
Number of ways 5 different cars can be parked in 5 parking spaces is 5!.
Remember:
This does not apply if there are identical objects or ordering does not matter.
由于美国数学基础教育的难度增加导致数学考试越来越难，但新gre数学复习考点都是高中时候学到的知识点，考生不要过于紧张，把基本概念弄明白，再记住一些新版gre数学必备的词汇，那么相信新版gre数学应该没有问题。
