2011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。下面就来看一下新GRE数学考试重点介绍。
新版GRE数学复习重要考点:Sum of Arithmetic ProGREssion
The sum of n-numbers of an arithmetic proGREssion is given by
S=nx*dn(n-1)/2
where x is the first number and d is the constant increment.
example:
sum of first 10 positive odd numbers:10*1+2*10*9/2=10+90=100
sum of first 10 multiples of 7 starting at 7: 10*7+7*10*9/2=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
The average of all odd numbers from 3 to 3135 is (3+3135)/2=1569
The average of all multiples of 7 from 14 to 126 is (14+126)/2=70
Remember:
Make sure no number is missing in the middle.
With more numbers, average of an ascending AP increases.
With more numbers, average of a descending AP decreases.
AP:numbers from sum
given the sum s of m numbers of an AP with constant increment d,
the numbers in the set can be calculated as follows:
the first number x = s/m - d(m-1)/2,and the n-th number is s/m + d(2n-m-1)/2.
Example:
if the sum of 7 consecutive even numbers is 70, then the first number
x = 70/7 - 2(7-1)/2 = 10 - 6 = 4.
the last number (n=m=7)is 70/7+2(2*7-7-1)/2=10+6=16.the set is the even
numbers from 4 to 16.
Remember:
given the first number x, it is easy to calculate other numbers using the formula
for n-th number: x+(n-1)
AP:numbers from average
all m numbers of an AP can be calculated from the average. the first number
x = c-d(m-1)/2, and the n-th number is c+d(2n-m-1)/2, where c is the
average of m numbers.
Example:
if the average of 15 consecutive integers is 20,
then the first number x=20-1*(15-1)/2=20-7=13 and
the last number (n=m=15) is 20+1*(2*15-15-1)/2=20+7=27.
if the average of 33 consecutive odd numbers is 67,
then the first number x=67-2*(33-1)/2=67-32=35 and the
last number (n=m=33) is 67+2*(2*33-33-1)/2=67+32=99.
Remember:
sum of the m numbers is c*m,where c is the average.
以上便是新GRE数学考试重点介绍，各位考生可以根据自己的情况参考复习，预祝各位考生考试成功。
