Xueba, I beg you to go and escort him quickly!

topic:

Starting from the definition of Young's modulus, according to the principle of light lever, the experimental measurement formula of Young's modulus is derived.

This question is just right.

Xu Heng probably thought about it, he wanted to organize his words.

"Any object will be deformed under the action of an external force. According to Hooke's law, the force per unit cross-sectional area within the elastic limit..."

"..."

"This experiment measures the elongation of the steel wire under the action of an external force F..."

"..."

"The mortgage coefficient of light leverage is 4D/b, substitute..."

"It was easy in the end."

Xu Heng didn't pause in the middle, and after he finished speaking, he said, "You must be different from those classmates in high school, right?"

Ling Yurou, "Huh? Why, why is it different?"

Xu Heng, "Your understanding and learning abilities should be far better than theirs!"

"Hey……!"

"They're really annoying."

Ling Yurou looked at Xu Heng with a half-smile.

"Forehead……"

She is embarrassed!

She was really ready to ask again just now!

But these words came to his lips, he didn't expect Xu Heng to say that.

She looked at the other two, who also curled their lips with embarrassment on their faces.

"That... that... the students in your Mathematics Olympiad competition class are outstanding students from all over the country! In the future, they will either be Tsinghua University or Peking University. Even if they enter Tsinghua University and Peking University, they will all be outstanding students..."

"If you look at it this way, it should be that the topic you are talking about is a bit difficult..."

Xu Heng shook his head, "This is not quite right! I taught the physics of the second year of high school to my classmates in the physics class of my original class, and they all understood it well!"

"Some grades are at the bottom of the grade!"

"And my high school is just a county high school."

Ling Yurou and the other two girls said, "Ah...%￥###￥..."

Embarrassing!

So this question, do you still ask?

They exchanged a look, then laughed awkwardly.

Xu Heng, "???"

Ling Yurou, "No, nothing..."

Eat until noon.

Xu Heng took out his phone.

There are a lot of missed calls and messages on it.

When Xu Heng entered the library, he switched to mute.

So just noticing it now.

After looking around, most of them were sent by Zhu Tiesen.

Long story short apology.

Xu Heng only replied Zhu Tiesen with a few words, "It's okay."

Zhu Tiesen immediately called, "Student Xu Heng, that... I'm really sorry, I..."

Xu Heng interrupted Zhu Tiesen, "Professor Zhu, that's it! I'm going to have lunch now."

hang up the phone.

Xu Heng and Ling Yurou went to the cafeteria together.

After a full meal, go to the classroom for lunch break.

He came to the classroom for lunch break.

As for other students, they can go back to the dormitory to rest.

Therefore, at this point, logically speaking, the classroom should be empty.

But when Xu Heng walked in, Dong Fangyuan was still studying here.

He was alone, in the classroom, and he didn't hear anything outside the window...

Xu Heng walked in and approached Dong Fangyuan, but he didn't even know it.

He is too serious and is concentrating on the problem.

Xu Heng tilted his head and glanced at it.

Reverse the order of a 17-digit number and add the resulting number to the original number.

Proof: At least one number in the obtained sum is even.

Xu Heng probably saw his problem-solving ideas and couldn't help reminding him.

"Assume that the numbers of the sum are all odd numbers. In the addition formula, the sum d+a of the numbers in the last column is an odd number..."

Just saying that, Dong Fangyuan immediately understood.

He raised his head abruptly and saw that it was Xu Heng, goosebumps all over his body.

"It's you?"

He laughed violently, looked down at the title again, followed Xu Heng's reminder, and continued, "The same is true for the first column, so the sum of the numbers in the second column b+c≤9."

"So the first two digits a, b and the last two digits c, d of the known number are removed, and the resulting 13-digit number still has properties: reverse its number, add the obtained number to it, and the number of the sum They are all odd numbers. Proceed in this way, each time removing the first and last two digits."

"." Finally, a single digit is obtained, and when it is added to itself, it is obviously an even number.contradiction! "

Xu Heng nodded.

Then go to the last row.

"what……"

I yawned and was just about to lie down and sleep for a while.

Dong Fangyuan immediately sat next to Xu Heng with his books and materials in his arms.

Xu Heng, "?"

Dong Fangyuan took a deep breath, "Thank you, student Xu Heng!"

He looked forward again, scanning the entire classroom.

"It turns out that the field of vision in the last row is so wide... I have been sitting in the first and second rows before, and I have never had such a field of vision."

Xu Heng smiled, "Why didn't you take your lunch break?"

Dong Fangyuan, "I'm used to it! If you have lunch break, why don't you do a few more questions?"

Xu Heng, "Aren't you afraid that a bad state will affect your performance?"

Dong Fangyuan smiled, "Student Xu Heng, maybe you can understand that I am training, how to improve the accuracy of the questions when I am not in a good state."

Xu Heng was stunned.

He really didn't expect Dong Fangyuan to say that.

He glanced at Dong Fangyuan, Dong Fangyuan smiled back, and said, "I think Xu Heng shouldn't have such troubles, right?"

"No matter what the question is, no matter whether you are in a good state or not, you will answer it fluently, right?"

"It's like addition, subtraction, multiplication, and division within one hundred. You don't need to use your brain at all. How can you tell if your condition is good?"

Xu Heng, "No, you guys are overthinking it! I'm not as amazing as you imagined, you all made me a myth! I just do the questions faster, after all, I know all these question types very well."

"Since it is clear, it will be done naturally."

Dong Fangyuan gasped, "So, compared with yours, my question bank is like a drop in the ocean!"

Xu Heng, "Uh..."

never mind!

Don't say it, don't say it!

You guys are getting better at rainbow farts.

Xu Heng fell asleep.

When he wakes up again.

Surrounded by strangers.

The previous group leader, Luo Jianing, Feng Hechuan and others were all two or three rows away from him.

They smiled bitterly at Xu Heng, "Brother Xu Heng, you are so hot now! Everyone rushed to sit in the first three rows, but now they all sit around you."

(Good) Xu Heng, "%￥#￥￥..."

Look around.

On one side is Dong Fangyuan, and on the other side is Wang Mengyao.

What is this called!

Has the tide turned?

???

Xu Heng sighed, thinking about changing positions, but the professor came in.

Another new professor!

But for Xu Heng, they are also old friends.

"Student Xu Heng! Good afternoon!"

Xu Heng smiled, "Hi, Professor!"

The other party said, "I'm going to call Professor Zhu first, he thought you were so angry that you didn't come to participate in the Math Olympiad!"

Angry is angry!

In fact, Xu Heng still cares about matters related to the face of the country.

Furthermore.

I can have the opportunity to go abroad to sign.

Kill two birds with one stone!

If there are no excessive things or special circumstances, he will not give up.

The professor went out to make a phone call, then came back and continued the class.

As for Zhu Tiesen, he ran to the classroom in a panic, looked at Xu Heng through the window, and smiled silly at Xu Heng.

Xu Heng smiled back.

Only at this moment did Zhu Tiesen know what is enough and enough is enough. If greed is not enough, it will only backfire.

His original intention was good, so Xu Heng naturally knew about it, so he didn't really get angry with him.

But there is still an attitude that should be there!

Xu Heng finally understood some things. It is not enough to refuse verbally, but to use practical actions to tell the other party that you are going to touch my bottom line!

It is very important to be a human being and have your own attitude!

!!!