1 definition

2 Mid-term formula

3 general term formula

4 summation formula

5 Determination method ① Definition method ② Middle term formula method ③ General term formula method ④ Sum formula method

6 attribute ① d > 0, increasing sequence; D<0, decreasing series

②a 1+an=a2+a(n- 1)=… ..

③ Positive integers M, N, P, K If m+n=P+k, then am+an=ap+ak.

④ Isometric term or arithmetic progression.

⑤ Equal sum still becomes arithmetic progression.

What is not filled in above can be filled in, or the related contents of geometric series can be listed one by one according to the above contents.