新gre數學考點介紹：set、排列、組合

　　新gre考試實施以來，不僅對寫作部分茫然不知所措，就連我們所擅長的數學也甚是擔憂，相信這其中的原因還是由于考生在新gre數學復習時沒有把基礎打牢。如果新版gre數學基本考點都沒有復習到，如何能拿到分數呢?所以說，想要新版gre數學考好，復習的時候一定要把基本概念和重要考點都弄扎實。

　　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.

　　由于美國數學基礎教育的難度增加導致數學考試越來越難，但新gre數學復習考點都是高中時候學到的知識點，考生不要過于緊張，把基本概念弄明白，再記住一些新版gre數學必備的詞匯，那么相信新版gre數學應該沒有問題。

　　新gre考試實施以來，不僅對寫作部分茫然不知所措，就連我們所擅長的數學也甚是擔憂，相信這其中的原因還是由于考生在新gre數學復習時沒有把基礎打牢。如果新版gre數學基本考點都沒有復習到，如何能拿到分數呢?所以說，想要新版gre數學考好，復習的時候一定要把基本概念和重要考點都弄扎實。

　　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.

　　由于美國數學基礎教育的難度增加導致數學考試越來越難，但新gre數學復習考點都是高中時候學到的知識點，考生不要過于緊張，把基本概念弄明白，再記住一些新版gre數學必備的詞匯，那么相信新版gre數學應該沒有問題。