2018年GRE数学重要考点（7）

　　无论什么考试只有掌握了考点，才能达到事半功倍的效果，今天课窝小编就为大家分享GRE数学重要考点，希望同学们都能熟记下来，争取考试中取得高分。

　　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.

　　Sequence of Numbers

　　A sequence is a set of numbers that follow a fixed pattern.The fixed pattern can be expressed by an equation or by a property.

　　Example:

　　A set of consecutive integers: 1,2,3,4,5(Fixed gap)

　　A set of consecutive even numbers:4,6,8,10,12 (Fixed gap)

　　A set of consecutive prime: 2,3,5,7,11(Fixed gap)

　　A set of consecutive power of 2:4,8,16,32,64(Fixed gap)

　　Remember:

　　A sequence can be in ascending or desceding order.

　　今天小编就和大家分享以上内容，希望大家能够熟练掌握，对同学们2018年GRE考试会有所帮助的，早日实现自己的留学梦!小编会继续更新GRE数学资料，GRE阅读难点，GRE考前指导，GRE填空资料等相关内容。