gre数学考试在新gre考试当中增加了一些难度,但是gre考生也不要太紧张,只要把一些gre数学基本概念掌握好,解题时就一定能轻松应对。 J) b* }5 g% W- ~, Z7 J9 @
排列组合
# k9 x# V& j1 S& K" H 排列数公式和组合数公式:* d# R3 G8 e( B6 {& I
乘法原理:4 \, S& y9 k; E
一件事的完成可以分成n个步骤,完成其第一步有m1种方法,完成第二步有m2种方法……完成第n步有mn种方法,那么完成这件事一共有N=m1*m2*……*mn种不同的方法。) V; }8 y& e$ `# l2 t. w( ^5 C+ g
例题.If all of the room numbers in a certain hotel must be even numbers, and if each of the numbers uses all four of the digits 3,4,5 and 8, what is the greatest number of four-digit numbers that the hotel can have?
) i, K% x) W c$ m# ` 例题.What is the total number of different 4-digit integers in which the units’ digit is an odd integer while the thousands’ digit is an even integer?
+ Z" ^/ S4 i, ~: g 例题.What is the total number of different 5-digit numbers that contain all of the digits 1,2,3,4, and 5 and
) E5 z, p( K% `/ Z3 Z" b+ y" S9 ?4 [ 1) in which none of the odd digits occur next to each other?- m% X, G Y: l4 f
2) in which none of the even digits occur next to each other?
9 i. ^6 _/ h8 R% m0 I6 k: X 平时,gre考生一定要注意gre数学基本概念的加强理解,因为无论gre数学考试怎样的题目都是从最基本的概念中演变而来的。 |