Chapter 256 Confrontation (Eight More)

With the start of this exchange conference, an old professor of the Department of Mathematics of Jingyun University presided over the exchange conference.

At the same time, accompanied by the leaders of the Provincial Education Bureau, the leaders of the education department also slowly took their seats.

After a polite greeting from the host, the students from the three provinces began to communicate.


To put it bluntly, this is a demonstration of “strength first”.

The three provinces reported their teaching achievements this year to the education department in a disguised form through exchanges between students.

So after the discussion started, everyone spared no effort to express themselves.

Although no classmates among the three provinces discussed the results of this Olympiad and the ranking results, everything has been revealed from the eyes of the students from the other two provinces.

And the classmates from those two provinces, as soon as they came up, they brought out the topic of the Olympiad for discussion, which was obviously provoking a declaration of war!

Xu Cong sat silently in the back row, looking at them quietly, seeing them clearly.

But at this time, the students in this province are not in the mood to look at the topics on the blackboard, they turn their heads from time to time and look at Xu Cong.

“Xu Cong is big! Hello! Hehehe!”

“Xu Cong is so handsome! He is tall! I want to give him a monkey!”

“Yang Kaixuan, does Xu Cong have a girlfriend?”

“You can debut right away, right?”

“Will Xu Cong go to the Film and Television Academy?”

They all winked at Xu Cong, and they were all discussing Xu Cong privately. They didn’t care about the students from the other two provinces.

The classmates from the other two provinces encountered this situation for the first time, so they were so embarrassed that they could show some respect, okay?

Are you arrogant and abandoning yourself? Why are you not active at all!

It is said that even if your province lost in exchanges before, it would not lose in momentum. What happened this year?

Is it really broken and broken?

do not!

If you are like this, how boring our two provinces are!

On the blackboard, this classmate from the province next door, after writing the topic, also looked to this side, but no one paid any attention to him.

A few seconds in a row!

So he could only say in embarrassment: “Ahem! Is everyone still a shadow of this year’s Olympiad? Or, after the Olympiad, everyone just left the question behind?”

The student’s voice was loud and resounding throughout the classroom, and Xu Cong also raised his head and glanced at the subject.

topic:

Find all quaternion real arrays (x1, x2, x3, x4) so ​​that the sum of any one of them and the product of the other three is equal to 2.

As soon as he finished reading it, he stretched out his hand to cover his face.

Embarrassing!

Isn’t this his problem?

Why do you always hold on to the questions of the Olympiad? There are so many!

It is still the topic of the Olympiad!

The previous ones were fine, but Xu Cong made this one, and he always felt very ashamed.

The most important thing is that he thinks that the simple question is so simple, are you worthy of it?

Of course, Xu Cong can probably guess the psychology of these students.

On the one hand, it is for deliberate provocation!

On the other hand, because this Olympiad is very difficult, it refreshed their understanding, can understand these questions, and make them feel very fulfilled.

“No one came to talk about it?”

“This is just a preliminary question! I didn’t have enough time for the exam before, but after I went back, I studied and researched and proved this proof question!”

“Is there any classmate to answer?”

This classmate was a little embarrassed. He stood on the stage and looked left and right. It was shocking that no one answered him. The scene was cold and embarrassing for a while!

As the host, the old professor couldn’t stand it anymore, and walked up to warm up for him and said, “Students, don’t you decide to come up and try it?”

“Review the old and learn the new…”

After a brief stalemate, a classmate suddenly stood up and stepped forward.

“This question can be set ×1×2×3×4=d, then xi2+d-2xi=xi(xi+(d/xi)-2)=0, so we get…”

On the blackboard, he wrote down (1-d) (i=1, 2, 3, 4) under xi=1±.

He continued to write, and then said: “Obviously it is d.”

Xu Cong glanced at the final answer he gave, and the answer was correct, but the process was very complicated.

He even fell into a misunderstanding, and it was not easy to get out of it. After finishing this topic, the classmate walked slowly.

“Wow…” Then there was applause.

At this time, Yang Kaixuan and He Junfei approached Xu Cong and asked: “This question is a good way to do it, but I always find it a bit complicated. Xu Cong, do you have a simpler idea?”

Xu Cong shook his head immediately, saying that he didn’t know.

He Junfei clenched his fists, and said unwillingly: “Then this is not showing them in vain?”

Xu Cong heard him say this and whispered to him: “Although the method is the same, his verification process is a bit more complicated, especially where it is on the second blackboard…”

Xu Cong pointed out the problem sharply.

At this time, the host looked at the audience and said to everyone: “What do you think of the proof of this question? Who has different opinions and suggestions?”

“Don’t be nervous, and don’t feel embarrassed. This exchange meeting is to promote mutual learning and integration, so everyone can speak freely.”

The voice fell.

Ten seconds…

Twenty seconds…

Still no classmates came forward.

The host twisted his eyebrows slightly, pushed his thick glasses, and said, “Since there are none, then we will move on to the next…”

Wow!

After listening to Xu Cong’s explanation, He Junfei suddenly wanted to understand another solution to this problem. He immediately got up, and under the attention of everyone, he strode to the blackboard.

Picking up the blackboard eraser directly, wiped out part of the other classmate’s problem-solving ideas.



“!!!”

There was an uproar at the scene, especially when the corner of his eyes twitched, and the place where he was wiped off was the step he was most proud of.

Because at this point, many students will fall into a misunderstanding and cannot continue to prove it.

Only he came around, he was just about to get up.

He Junfei said to him: “This approach is too complicated! Although the idea of ​​this question is correct, most of the students have fallen into a misunderstanding.”

“Here! Everyone, please see, since there are five situations.”

He Junfei quickly wrote:

In the first case, x1=x2=×3=x4=1+√(1-d), then d=(1+√(1-d))⁴≥1≥d, so d=1, x1× 2x3x4=1.

“Reverse directly, according to”

“We are looking at the second situation!”

In the second case, three of x1, x2, x3, and x4 are 1+√(1-d), and one is 1-√(1-d), then d=(1-√(1-d))( 1+√(1-d))3=d(1+√(1-d)2), so d=0, so three of x1, x2, x3, and x4 are 2, and one is 0, but O+ 2*2*2≠2, so d=0, it is impossible.

“According to this, you can directly negate the second case. If you follow what the previous student said, it will be too circumstantial! And it is very likely to go wrong!”

His voice was loud and loud, and He Junfei’s direct and sharp words made everyone look at him.

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