By analyzing the quantitative relationship module in the recruitment of civil servants in recent years, candidates are often prone to make mistakes in the examination of the number series. One of the reasons is that most candidates didn't pay attention to the series problem during the preparation. Some candidates can't remember the formula related to the series problem, while some candidates know the formula but don't extrapolate and improvise. In the civil service examination, arithmetic progression question is the most common question. Let's discuss some knowledge about arithmetic progression.

This kind of problem is easy to identify, and it is necessary to understand the formula in the application of problem-solving methods. Here are a few examples to explain in detail the problem of arithmetic solving sequence.

Example 1. (Multiple-choice questions) A magazine is no more than 200 pages, of which the last page is an advertisement, two consecutive pages are separated by X pages, three consecutive pages are separated by X- 1 page, and so on, and the last six consecutive pages are separated by 1 page. How many pages of advertisements does this magazine have at most?

A.9 1

b96

C. 105

D. 120

Analysis: judging from the characteristics of the topic, this topic examines the sequence. According to the headline information, the number of advertisement pages in the whole magazine is arithmetic progression, and the total number of pages is 1+2+3++(X+ 1). Arithmetic progression is used to find the sum of the first n terms, that is, the sum of the first X+ 1 positive integers is false. The number of non-advertising pages is 1+2+3+X, that is, the sum of the first x positive integers is false. The enumeration shows that when X= 14, the sum of the first 14 positive integers is 105, and the sum of the first X+ 1 5 positive integers is 120, and the number of pages added is. When X= 13, the sum of the first 13 positive integers is 9 1, and the sum of the first X+ 1 4 positive integers is 105, and the total number of pages is/kloc-. Therefore, choose the c option.

Example 2. (multiple choice questions) On the premise of doing a good job in epidemic prevention, a factory resumed production in an all-round way. On 1 day after the resumption of work, the production capacity was restored to 60% before the shutdown. Every four days after the resumption of production, the daily production capacity is increased 1000 pieces/day compared with the previous four days. It is known that 80 days after the resumption of work, the total output is equivalent to 88 days before the shutdown. When will the total output reach 6,543,800 pieces after the resumption of work?

A: 54

b56

C.58

Cao 60

Analysis: From the characteristics of the topic, we can know that this topic examines the sequence problem. If the daily output before the resumption of work is X, then the daily output in the first four days after the resumption of work is 0.6x, and four of the 80 days are a cycle. According to arithmetic progression's general formula, the daily output in the last cycle, namely the 20th cycle, is 0.6x+(20- 1)? 1000。 So what is the total output in 80 days? 20=48x+ 19000？ 40, meaning 48x+ 19000? 40=88x, we can know that x= 19000, and the daily output in the first cycle after returning to work is 19000? 0.6= 1 1400。 Alternative option, preferably an integer number of cycles. Option b, 56 days means 14 cycles, and the daily output of the last cycle is11400+(14-1)? 1000=24400, so the total output in the first 56 days is (1 1400+24400)? 2? 56= 1002400, which just exceeds 1 10,000 pieces, but it cannot be exceeded on the 55th day. Therefore, choose option B.

Example 3. (multiple choice questions) A financial institution issued 9? Speciality and novelty? Enterprises * * * issued loans of 45 million yuan. If the amount of loans obtained by these nine enterprises is arranged from less to more, it happens to be a arithmetic progression, with the third enterprise getting a loan of 4.2 million yuan and the eighth enterprise getting a loan:

0.62 million yuan

6.60 million yuan

C.720 million yuan

760.00 million yuan

Analysis: From the characteristics of the topic, we can know that this topic examines the sequence problem. Nine enterprises * * * issued 45 million yuan, and the amount increased in an arithmetic series. According to the sum formula of arithmetic sequence, sum = median? The number of items, we can know that the fifth-ranked enterprise is in the middle, getting 4500? 9=500 (ten thousand yuan). According to the topic, the third-ranked enterprise gets 4.2 million yuan, so what is the tolerance of arithmetic progression (500-420)? (5-3)=40 (ten thousand yuan), and the eighth-ranked enterprise gets 500+40? (8-5)=620 (ten thousand yuan). Therefore, choose option a.

The above three examples all belong to the concrete application demonstration of arithmetic progression. If you remember the formula in detail and understand the application of the formula in the subsequent preparation, you will get twice the result with half the effort, and the road to preparation will be long and arduous. I hope everyone will stick to it.