Chapter 293: Legendary senior

Chapter 293
In the National High School Mathematics League, the test questions mainly cover four branches of mathematics: plane geometry, algebra, elementary number theory, and combinatorial mathematics.
Of course, not only the math competition, but also the main content of these four aspects in the imo field. But this is not to limit a certain type of problem, you must use a certain aspect of knowledge to solve it. Mathematics is an internally interconnected subject. A problem can be solved by algebraic methods, or perhaps by number theory. Mathematics is always full of infinite possibilities and endless fun.
For ordinary people, the formula that feels big at a glance may have a different aesthetic for this group of students participating in competition training.
…………
On the podium, Old Tang held the tutorial book and wrote the topic on the blackboard first.
[Given a positive integer n, each of the six vertices of the regular hexagon is written with a non-negative integer, and the sum is n. Now proceed as follows: erase the number on one vertex, and then write the number on two adjacent vertices For the absolute value of the difference of, find all n, so that no matter what integers are at the beginning, a series of operations can be performed so that the number on each vertex is zero. 】
From the perspective of the question, this question is not simple, and it is quite different from the various question types encountered in high school. It is no wonder that only one of the thirty-odd people who participated in the training was able to solve it.
Comrade Tang scribbled the steps on the blackboard while explaining to everyone in the audience.
He first drew a regular hexagon.
"First, according to the meaning of the question, we assume that the parity of the six points of the hexagon is even, odd, odd, even, odd, and odd in counterclockwise order. In this case, no matter how you operate, these six numbers The parity will not change, so..."
"...According to the above process, we can temporarily draw a proposition: as long as the initial six numbers are not even, odd, odd, even, odd, odd, and not all even numbers, then it must be made through a limited number of operations All numbers are equal to zero."
"This proposition is just written by ourselves, and we don't know its true or false. Next, we need to prove that this proposition is a true proposition through classified discussion. Looking at my discussion steps, let's start with..."
"...Do you understand the process on this blackboard? I will wipe it if I understand it!... Next, we will discuss the situation of
a2-a6
=k, since o≤a2, a6≤k, Then we might as well set..."
Click! Click!
The two blackboards were wiped twice by Tang before and after, and dozens of lines were written in dense formulas. It took almost half an hour before Tang to prove the problem that was extremely complex in terms of thinking and process.
As long as two-thirds of the students participating in the training are still in a dazed state.
who am I? where am I? Why should I join this training?
After being stunned for three consecutive times, each of them turned their eyes to the lowly tall boy in the front row. His name is Chen Gong, and he has always been ranked first in age, and he is a proper student. He is also the only student in the thirty-odd people who has solved this extremely complicated problem.
Some people say that perhaps Chen Gong will be the second student to become the top student in the college entrance examination after Cheng Nuo in Qingcheng Second Middle School.
The great is the great god, it really is not comparable to our group of mortals!
In the gazes of everyone's admiration, Chen Gong's expression remained unchanged, without any proud expression on his face.
To be honest, he only thinks this is just a very basic operation. He won the first prize of the SMU, entered the national team, and won the imo gold medal, which is his goal in the future stage.
After talking for so long, Comrade Tang was also a little dry. He unscrewed the bottle cap of the thermos cup on the lecture table, took a sip, supported the lecture table with both hands, and habitually asked, "Do you have any questions about this question? If not, then we..."
Before Tang finished speaking, he saw a hand slowly raised in the back of the classroom, and a slightly lazy voice echoed in the classroom, "Teacher, I have a question."
Huh huh!
Looking at them all together, they turned out to be a handsome but unfamiliar face reflected in their faces.
Old Tang, who was standing on the podium, trembled when he saw the figure raising his hand in the back row of the classroom, and then he couldn't help but shook his head and said with a smile, "Cheng Nuo, it turned out to be your kid."
Cheng Nuo?
The whole class froze for a few seconds, and then it boiled completely.
Senior Cheng Nuo is a legendary existence in their Qingcheng No. 2 Middle School, and a goal pursued by Wu Mathematicians. But because Cheng Nuo’s counterattack was too short, the school has really seen
"Senior Cheng Nuo, it's senior Cheng Nuo. I finally saw alive!"
"It turns out that the senior is not the legendary Diaosi Xueba, I thought the senior has always been a fat house."
The two girls huddled together for a chattering discussion, and their eyes still looked at Cheng Nuo from time to time, but the content of the conversation made Cheng Nuo a black line.
The shadow of the famous tree. I have to say ~EbookFREE.me~ Cheng Nuo's reputation is really big enough in Qingcheng Second Middle School. Some students may not know the name of the principal, but for the legendary senior Cheng Nuo, no one knows. For this reason, the classroom of Class 18 used to be a place for competition and training, partly because of the immortal spirit of Cheng Nuo, who has a perfect score in mathematics for the college entrance examination.
When Old Tang said Cheng Nuo's name, even Chen Gongxueba, who had been sitting in the first row for a long time, turned his head abruptly and fixed his eyes on the young man who was not a few years old.
Is he... Senior Cheng Nuo?
"Okay, everyone, be quiet, be quiet." Comrade Tang motioned everyone to be quiet, "Your senior Cheng Nuo will give a lecture in our school's auditorium two days later. If you have any questions, you can leave it there. time."
Then he said to Cheng Nuo, "Sit here for a while, and wait for me to tell them the last few questions, and then talk to you."
Cheng Nuo smiled and nodded.
The classroom became quiet.
Comrade Tang continued the previous question. He pointed to the blackboard and repeated what he said just now, "Do you have any questions about this question? If..."
In the back row, Cheng Nuo raised his hand again.
Old Tang was a little confused, "Cheng Nuo, I didn't mean..."
Cheng Nuo smiled bitterly, "Teacher, I don't mean anything else. It's just that I have a little bit of my own opinion on the question you just talked about."
Cheng Nuo's flat voice echoed slowly in the classroom.
Old Tang looked stunned. The familiar feeling in the memory resurfaced.
Sure enough, Cheng Nuo was still the same Cheng Nuo, not changed at all.
He motioned to Cheng Nuo to come up and cursed with a smile, "You are going to tear down my desk as soon as you come over!"
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