Chapter 13 Ding Ping’s surprise

On Monday, classes for senior high school students continued as usual.

As the top student in the grade this time, Lin Xiao also enjoyed the treatment of a top student. Even the female classmates sitting in the back seat came to ask him math questions.

And his appearance is also a bit handsome. That is to say, the students in their rocket class are all good students and they focus on their studies. If he goes to a regular class, there may be a few girls in the class. Chase him.

In this way, he gradually lost himself in the "Lin Xueba" one after another... Ahem, of course this is impossible, he just believes more and more that learning is indeed the most important thing.

So, he studied hard for another whole day, and he didn't stop until the afternoon, when the math competition training class started.

Then, he took the league papers from last night, along with paper, pens and teaching materials, and headed to the training class.

Jiang Jie was also going, so he happened to be walking on the same road as Jiang Jie.

Jiang Jie looked at Lin Xiao who walked with him to the laboratory building, and couldn't help but asked in confusion: "Lin Xiao, are you coming to the laboratory building too?"

Lin Xiao nodded, "Yes, Teacher Ding Ping asked me to come to the mathematics competition training class, so I came."

Jiang Jie was stunned for a moment, then said "I heard you right" and said, "Teacher Ding, have you been asked to come to the training class?"

"yes."

Seeing Lin Xiao nodding, Jiang Jie became even more confused: "What about Xu Lin? He's not here?"

"He won't come. Teacher Ding only called me here alone. I was at Teacher Ding's place last night. He gave me some guidance and then asked me to come to the training class."

Jiang Jie was even more puzzled. Teacher Ding actually tutored Lin Xiao alone?

He couldn't understand.

What attracted Teacher Ding to Lin Xiao?

Is Lin Xiao very talented in mathematics?

Isn't it just that he got full marks in this exam? He could have gotten full marks in the exam, but when he got to the last question, he saw that Lin Xiao had already finished and handed in the paper. He was a little anxious, so a little problem occurred. 2 points were deducted.

Otherwise, he would definitely be able to get full marks.

What's more, in the past, when Lin Xiao didn't get full marks, he also got full marks.

So he felt so depressed all the way.

Soon, the two arrived at the training class classroom, where there were already about a dozen students, mostly sophomores, because more sophomores participated in competitions.

Ding Ping was already sitting on the podium. When he saw Lin Xiao arriving, he waved to Lin Xiao and said, "Classmate Lin Xiao, come here."

"Teacher Ding." Lin Xiao greeted and walked over.

When Jiang Jie saw that Ding Ping actually called Lin Xiao over, with a smile on his face and looked very friendly, he became even more confused. What happened to Ding Ping that he suddenly favored Lin Xiao so much? Already?

So he pretended to be Lin Xiao's friend and got closer, wanting to hear what Ding Ping had to say to Lin Xiao.

"Did you make that paper after you went back last night?" Ding Ping asked with a smile.

"Done."

"Is the last question difficult?"

"Well, it was quite difficult. It took me more than sixty minutes to write it."

"Well, don't be discouraged. This question is actually... huh?!"

After listening to the first half of Lin Xiao's sentence, Ding Ping thought that Lin Xiao really didn't do it, so he just finished half of what he said when he suddenly came to his senses.

"You said you wrote it out?!"

Lin Xiao nodded: "Yes, I've written it down."

"You... take it out and show it to me." Ding Ping had been shocked by Lin Xiao's talent last night, and now he heard that he had actually solved the "Legendary Question 6", and his heart suddenly I was so surprised that I felt a little embarrassed to speak.

When Lin Xiao saw Ding Ping's reaction, he couldn't help but wonder what was the origin of the question last night?

He has always wondered why he was rewarded by the system after writing this question. Although he did use a method that he himself thought was quite brilliant, the system also said that that question was very important to him. At the current stage, it is quite difficult.

Maybe it's mainly because that question is quite difficult?

Quickly, he took out the paper and handed it to Ding Ping.

Ding Ping immediately turned to the last page and started reading.

Jiang Jie next to him was also a little curious as to how difficult the question was to make Teacher Ding react like this.

Soon, he saw this question and noticed the mark behind the question number. He couldn't help but said: "It's actually an IMO question? The sixth question in 1988... Hey, I remember this is not that particularly difficult question. ?"

After being reminded by Jiang Jie, Lin Xiao noticed that the source of the question was marked after the question number.

"It turns out it's an IMO question. I asked why it's so difficult! I almost thought the league tests were all questions like this." He was also a little surprised, but he finally felt relieved. In this way, the league looks pretty good. It's simple.

But after hearing what he said, Ding Ping asked doubtfully: "Don't you know this question is an IMO question?"

Lin Xiao: "I don't know, I didn't notice the label behind it."

Seeing that Lin Xiao didn't look like he was just pretending, Ding Ping couldn't help but wonder, could he really do this question?

Ding Ping began to watch Lin Xiao's proof process from the beginning.

Well, the method of proof by contradiction is used. Assume that K is not a square number, and then prove that this assumption is contradictory, that is, prove that K is a square number, thus completing the proof. Then, substitute the formula into it, merge similar terms, and simplify the entire formula. into the form of a quadratic equation, followed by...

Seeing this step, Ding Ping's brows gradually wrinkled.

The methods used in this problem-solving idea are... Vedic's theorem and the infinite descent method.

This method is also called Vedic jumping, which is a new problem-solving method that emerged from the IMO competition that year.

In the 1988 IMO, a contestant used this method for the first time to solve a number theory problem that was considered extremely difficult. Therefore, that contestant won the special prize of that year's competition, and this solution The problem-solving method has also become a problem-solving method that students who participate in the Olympiad in the future must master.

This kind of problem-solving idea actually uses knowledge at the junior high school level, but if you want to use these two methods to the extreme, it cannot be written by students at the junior high school level. Later Fields Medal winner Terence Tao, at the time He was only 12 years old when he participated in the IMO and won the gold medal. At the age of 12, he was in the sixth grade or the first year of junior high school in China. But can this be said to be at the junior high school level?

Obviously impossible.

Ding Ping thought of what Lin Xiao had just said. He didn't know that this question was an IMO question. Does this mean that he also came up with this problem-solving idea?

If this were true, that would be incredible. If Lin Xiao had been in that competition, wouldn't he have been awarded the special award?

But is this true?

Ding Ping thought about the talent Lin Xiao showed last night, and finally chose to believe in him.

In any case, believing in a student is what he should do as a teacher.

However, Jiang Jie next to him didn't think so.

He had understood this question before and knew how difficult it was, but now Lin Xiao actually said that he did not know this question and solved it using this method.

Lin Xiao said that he didn't know about such a coincidence. Does that mean he really didn't know?

He felt that Lin Xiao must be faking it.