论文部分内容阅读
设｛ａｎ｝是以ｑ为公比的等比数列，其前ｎ项和为Ｓｎ，若１≤ｍ＜ｎ，则易知 Ｓｎ＝Ｓｍ＋ｑｍＳｎ－ｍ．（１）特别地，当ｍ＝１而ｎ＞１时，有 Ｓｎ＝ａ１＋ｑＳｎ－１．（２）这是等比数列的一个简单性质，容易推出其逆命题也成立．下面举两例说明（１）和（２
Let {an} be the geometric progression with the common ratio of q, and the sum of the first n terms is Sn. If 1≤m1, there is Sn=a1+qSn-1. (2) This is a simple property of the geometric progression and it is easy to introduce its inverse proposition. Here are two examples (1) and (2)