新GRE数学考点：排列 组合.

　　今天针对新gre数学复习，小编给大家整理的是关于排列、组合的相关内容，这些概念在考试中一定会考到的。希望考生能再接再厉，取得一个好成绩，突破新gre数学难的困境。

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　　新gre数学复习重要考点：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.

　　新gre数学复习重要考点：Permutation with Selection

　　The number of ways n objects drawn from a collection of m distinct objects can be ordered is m!/(m-n)!.

　　Example:

　　Number of ways a queue of length 3 can be formed from a group of 5 people is 5!/(5-3)!=5!/2!=5*4*3=60.

　　Number of possible top ten list for 150 movies is 150!/(150-10)!.

　　Remember:

　　This does not apply if there are identical objects or ordering does not matter.

　　新gre数学复习重要考点：Combinations

　　Number of ways we can select n objects from a group of m distinct objects is m!/(n!*(m-n)!).

　　Example:

　　Number of possible ways to pick 4 oscar nominations from a list of 50 movies is 50!/(4!*(50-4)!)=50!/(4!*46!)=50*49*48*47/24=230300.

　　Remember:

　　This does not apply if there are identical objects.

　　俗话说：“工欲善其事必先利其器”。有一部分考生认为新GRE数学具有一定的难度，这其中的原因是由于考生在复习时没有把新gre数学的基础打牢。想要新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。