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

Did you get it done with two sentences?

Can you respect Professor Zhu and these topics?

The driver started to get goosebumps all over his body.

He couldn't help stepping on the gas pedal.

"hiss……"

He has seen what Zhu Tiesen often reads about the topic!

That can no longer be described with titles or numbers!

He even suspected that his studies were all for nothing!

That is simply a bible!

But in Xu Heng's hands, it was so easy and very simple.

......... 0 ...

is that a lie!

The driver struggled internally.

But Zhu Tiesen smiled happily, "Hahahaha...that's right, that's right!"

He was actually right!

There is also a proof question on the test paper.

Given n≥2, r(k) represents the remainder of n divided by k, σ(k) represents the sum of positive factors of k, find r(1)+r(2)+…+r(n)+σ( 1) + σ(2) + ... + σ(n).

Xu Heng is still at his fingertips.

"Professor, how did you see these questions?"

Zhu Tiesen frowned, "What's the matter, is there any problem?"

Xu Heng waved his hand and smiled deeply.

Zhu Tiesen, "???"

"Student Xu Heng, what do you mean?"

Xu Heng, "You are a professor, don't forget your identity! Just look at this?"

What does Xu Heng mean between his words?

You deliberately found the topic to test me!

As a professor of the Department of Mathematics of Peking University, you must not look at such a simple topic!

Zhu Tiesen, "Ah..."

He kind of got to Xu Heng's point.

He smiled awkwardly, not embarrassed to expose it.

Although these questions are here to test Xu Heng, they are also relatively difficult questions that he has been exposed to!

It's not as simple as Xu Hengkou said!

hiss……

He didn't accept Xu Heng's words, but said, "Excuse me?"

Xu Heng, "Obviously, r(k)=nk[n/k], so r(1)+r(2)+..."

"On the other hand, for any positive integer k ≤ n."

"Exactly [n/k] of 1, 2, ..., n are multiples of k, so k is repeatedly calculated at σ(1)+σ(2)+...+σ(n) [n/k] time, so..."

“然后将上述的两个以综合，就可以知道r（1）+r（2）+…+r（n）+σ（1）+σ（2）+…+σ（n）=n2。”

It is such an understatement to say it from Xu Heng's mouth.

The driver didn't understand at all, abaaaba, it felt like he was listening to the bible!

But Zhu Tiesen was particularly shocked when he heard it.

Is this still available?

This guy is useless to play toilet paper!

Just give the steps and answers directly!

Say this question is difficult, and it is not that difficult!

But keep it simple!

You can't do calculations in your head directly, the steps and answers are given by oral calculations!

Zhu Tiesen didn't know what to say for a moment.

He is a professor in the Department of Mathematics of Peking University, and he has seen countless talented students, but this is the first time he has seen someone like Xu Heng.

He is over 50!

I have been teaching at Peking University for more than 20 years!

Already numb to the geniuses of Peking University, but today, Xu Heng let him find out what shock is.

Seeing that Zhu Tiesen was silent, Xu Heng smiled.

"There is a second method, does the professor want to listen?"

……

PS: Thank you [tail number 8658] [Lin] for your support!

------

My girlfriend hasn't been fixed yet, and she won't be able to accompany me for New Year's Eve. This is destined to be a cold night...

Gritting my teeth, I continued to code crazily. I hope that during the Chinese New Year, I can get back together with her.

There will be updates later, please support us!Thank you everyone!three.

Chapter 137

Zhu Tiesen hasn't recovered from this side yet!

Xu Heng came up with another solution?

Zhu Tiesen, "!!!"

The driver looked at Xu Heng's calm expression through the rearview mirror, and he was in a bad mood.

I rely on!I rely on! !I rely on! ! !

Fortunately, I admitted my mistake in time!

Fortunately, Peking University was looking for someone at that time!

This is really a super peerless genius!

Looking at Zhu Tiesen again, what kind of generosity is this, a peerless genius who has never seen it before?But he was still stunned.

The driver is very observant.

He had never seen Zhu Tiesen like this.

Generally speaking, when Zhu Tiesen discusses problems with students, he is very comfortable!

But today, the driver clearly saw the micro-expression on Zhu Tiesen's face changing.

Xu Heng also noticed this.

"Cough cough!"

But his words have been spoken.

He originally thought that Zhu Tiesen, as a professor at Peking University, should do some research.

Know the second way to solve the problem, shouldn't it?

But what does he mean by this?

Or, did he neglect this question?

Ah!

Maybe it should be... that's it!

Zhu Tiesen came back to his senses, feeling a little embarrassed, "Ahem, say it!"

Let me say, just let me say, why are you pretending to cough...

Hey……

It's over!

All of a sudden exposed!

Xu Heng regretted it, he shouldn't have said the last sentence.

But having said it all, you can't be hypocritical.

"You can remember that rn(k) represents the remainder when n is divided by k, then rn(k)=k{n/k}."

"Let f(n)=rn(1)+rn(2)+...+rn(n)+σ(1)+σ(2)+...+σ(n), then..."

"..."

"We discuss the value of k({(n+1)/k}-{n/k}), in fact..."

"..."

"Finally, f(n+1)-F(n)=2n+1 can be obtained."

"Then it's easy to get f(2) = 4, which in turn gives f(n) = n2."

Xu Heng's speech speed is just like this car, when it gets on the high speed, it speeds up!

Zhu Tiesen could barely keep up with his thinking.

Xu Heng's voice stopped abruptly.

His shock, from head to toe.

Looking at this question, he was silent for a while.

He has seen too many Peking University math geniuses.

When I was a few years old, I participated in the Mathematical Olympiad, and was invited to participate, and won No.1!

In junior high school, he won multiple first prizes in national and provincial mathematics competitions, was a league champion, entered the provincial team, and entered the national training team, etc...

In Peking University, such students are rare.

But if it is compared with Xu Heng, it will look very bleak!

Zhu Tiesen looked at Xu Heng, "Student Xu Heng, can I ask you a question?"

"Have you really never participated in any competitions from elementary school to junior high school and then to high school?"

"I heard that your grades were not satisfactory before. Did you... hide it on purpose?"

Xu Heng smiled, "Professor Zhu, you have too many questions."

"Everyone has to have reservations, doesn't they?"

"Don't break the casserole and ask the end!"

Zhu Tiesen opened and closed his mouth.

He didn't ask any more questions, but took out a pen and wrote and drew on the straw paper.

He is analyzing these two solutions of Xu Heng.

Xu Heng played with his mobile phone for a while, and when he got tired, he went to sleep.

Zhu Tiesen muted the phone.