针对新版gre数学复习,将每天为大家整理一个重要考点,希望大家能够将这些重要考点系统地记住,在考试中取得一个好成绩,突破新gre数学困境。
新版gre数学复习重要考点:Sum of Arithmetic Progression(数列求和)
The sum of n-numbers of an arithmetic progression is given by
S=nxdn(n-1)/2
where x is the first number and d is the constant increment.
example:
sum of first 10 positive odd numbers:101+2109/2=10+90=100
sum of first 10 multiples of 7 starting at 7: 107+7109/2=70+315=385
remember:
For a descending AP the constant difference is negative.
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。
AP
Average of n numbers of arithmetic progression (AP) is the average of the smallest and the largest number of them. The average of m number can also be written as x + d(m-1)/2.
Example:
The average of all integers from 1 to 5 is (1+5)/2=3
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