First, we should master two important series: arithmetic progression and geometric progression, focusing on their properties, the solution of the general term formula and the solution of the sum of n terms (formula). These two series are frequently tested questions. You must master it skillfully!

Second, learn how to find the commonly used formula an of series (mainly including definition, superposition, overlapping multiplication, series construction, conjecture and mathematical induction) and how to find the formulas N and Sn (formula method, split term elimination method, dislocation subtraction method, grouping summation method, etc.). ), at the same time, accumulate and summarize more problems in this area.

Third, if you want to get high marks, you must accumulate some commonly used scaling formulas and prove some inequalities about sequence.

The first and second are the key points and the foundation, so we must master them! As for the third one, you have to accumulate it slowly! Note: when seeking an or sn again, we need to discuss it in different categories, n= 1, a 1=s 1.

N & gt=2, an=sn-s(n- 1) Just pay attention to the details!