The top student must be diligent

Station B is also known as Big B. There are many people studying here. Naturally, there are also many people studying mathematics. Some videos that specifically talk about mathematical problems often get a good number of views.

After all, there are many students nowadays. When watching a video and suddenly come across a math problem, they might try to see if they can solve it.

However, the content in this video is slightly different from those videos dedicated to the topic in that it takes place in a university classroom.

This question was posed by a mathematics professor at Huaguo University of Science and Technology. The protagonist in the video is Xiao Yi, who caused a stir on various online platforms at home and abroad for solving a world-class mathematics problem some time ago. In this video, he solves this problem in three ways.

This immediately attracted many netizens to click in.

Although, they are definitely not as powerful as Xiao Shen, but they also want to test the gap between themselves and Xiao Shen.

"If I can do it using three methods, does that mean I = Xiao Yi?"

In a mathematics laboratory at Beijing University, Chen Beihua, who was fishing openly, thought happily.

Xiao Yi used three methods to solve this problem, and he also used three methods to solve this problem.

He = Xiao Yi.

Just tell me if there is something wrong!

He testified that this equation is completely true as he is a doctoral student in mathematics at Beijing University.

Ahem, just kidding.

Of course, as a doctoral student in mathematics, he is quite confident, and as a functional analysis practitioner, his foundation is quite solid.

What's more, how difficult can the questions asked in class be?

Once you click on the video, a lot of barrages will appear.

[I’m thinking of a trade fair]

[There are three methods that can be used for this question? 】

[Come in to see my idol]

[The owner of the up is actually a student of Hua Luogeng’s class at HKUST? Are you still classmates with Xiao Shen? Envy]

【……】

Looking at these barrages, Chen Beihua raised his eyebrows.

It seems that this question is really difficult?

Finally, he focused his eyes on the blackboard in the video and looked at the question.

"Huh? It's actually a limit question related to prime numbers? It looks like something."

Chen Beihua rubbed his chin.

He paused the video, thought for a moment, then took out his pen and started writing.

After a while, he completed the first solution.

"Well, the most important thing is the transformation at the beginning. This is the key point."

"The next step is to use the prime number theorem and Stolz's theorem. This question is quite interesting."

"However, the second method..."

Chen Beihua was in trouble.

It is more difficult to break through previous thinking and find a second solution to a problem.

The inherent inertia of the human brain makes it always difficult to break through this inertial thinking and find a second way to solve a problem after completing it.

Probably if the brain cells have their own ideas, they will probably think: Is there something wrong with this person? The problem has been solved, why should we think about the second solution?

Therefore, if you want to come up with the second solution, you must first overcome this inertia of the brain.

However, as a doctor of mathematics, Chen Beihua's thinking ability is relatively stronger than ordinary people, so after spending almost ten minutes, he thought of the second method.

"Finally done!"

He breathed a long sigh of relief, and a smile appeared on Chen Beihua's face again.

It seems that he is still pretty good, being able to come up with such a showy second method.

But then, his expression became sad.

This third method...how to do it?

He racked his brains just now to come up with the second method, the third method... God knows how much time it will take him.

After thinking about it tentatively, he finally gave up.

"Forget it, don't think so much. It's good to be able to come up with two methods. At least it's equal to two-thirds of Xiao Yi!"

After comforting himself in his heart, he raised his head and clicked on the video that was paused just now, wanting to see what Xiao Yi's three methods looked like.

In the video, Xiao Yi left his seat and came to the blackboard.

"Come on! Let me see how long it will take Xiao Shen to solve this problem!"

Chen Beihua had a feeling of comparison in his heart. It took him about three minutes to figure out the first method. How long would Xiao Yi use it?

However, the next moment, he found that he was defeated.

After Xiao Yi went up, he started writing as if he didn't even think about it.

Chen Beihua was dumbfounded. Is this what he wrote? ?

Watching Xiao Yi complete the first method, he began to comfort himself: "It must be because I have already studied for a Ph.D. and haven't been exposed to this type of problem for a long time, so it took me three minutes to complete it."

"For the second method, Xiao Yi has to think about it for a while, right?"

As a result, the next moment, he saw Xiao Yi start a new line and start writing the second method, and it looked like... the second method Xiao Yi used was better than the second method he had just thought of. Be more "showy".

The second method he used contains some more advanced things, which are definitely not something that can be learned in freshman mathematical analysis anyway.

However, Xiao Yi's second method only used the most basic methods learned by freshmen, and used them to the extreme, and finally completed the problem.

"This is really awesome..." After watching for a moment, Chen Beihua finally sighed in his heart.

No, really no.

At least, his mastery of these very basic things has declined a lot.

This is very common. He knows that some mathematics professors may even forget the root formula of a quadratic equation.

After all, people are not computers. It is difficult to remember things from many years ago unless they are used frequently.

"So, how will Xiao Yi solve the third method?"

Giving up the comparison, he began to watch the video with an apprentice heart.

After a while, Xiao Yi in the video also began to write the third method on the other side of the blackboard.

As Xiao Yi wrote the definition first, Chen Beihua was immediately surprised: "This is... the sieve method? You can actually think of using the sieve method to solve this problem..."

"Yes, there is no problem at all. w(n) itself represents the number of prime factors of a positive integer... Damn, it's great!"

Chen Beihua slapped his thigh and was completely convinced.

He studies functional analysis, which can be applied in many places, whether it is number theory or algebraic geometry, so he also knows about the sieve method.

This is simply...

"Old Chen, what are you doing? You look so excited."

At this time, one of his fellow students saw him like this and walked up to ask.

"Oh, Old Liu, I saw a video related to Xiao Yi. Take a look. It feels so awesome!"

Chen Beihua replied.

Liu Dongchen came up to him immediately after hearing this, and started to yell at the same time: "Old Chen, you are not nice enough, don't you know that Xiao Shen is my idol now? Why didn't you send me his video when you saw it?"

Chen Beihua rolled his eyes: "I just saw this video, okay."

This Liu Dongchen is also one of the beneficiaries of Etale's algebraic variety self-defense theory, and then he began to call himself a super fan of Xiao Yi some time ago, and he looked like a dog, which made people in their laboratory hate him.

Humph!

Isn't it just relying on this theory to get a paper that can be published in the first district, what's the big deal?

It's not the top.

Chen Beihua said that he was definitely not jealous.

"Let me see..."

Liu Dongchen came up and took a look.

"Hmm... Is this a limit problem? It should be freshman mathematical analysis, I remember Xiao Shen just entered the school this year."

"Oh my god, he even brought in prime numbers. Freshmen are doing this kind of problem? Do I need to use the prime number theorem to solve it?"

At first, Liu Dongchen was a little surprised at the difficulty of this problem, and then he saw Xiao Yi's first solution. He clapped his hands and said happily: "Yes, it is indeed necessary to use the prime number theorem. It seems that my skills are still as good as before."

Chen Beihua sneered.

He thought so just now.

Then Liu Dongchen saw the second method.

Then, just like Chen Beihua, Liu Dongchen was shocked by the basic methods that almost used the limit here: "Oh my god! Can the squeeze theorem be used like this? Damn, if I knew this trick when I took the entrance examination, I wouldn't have lost points on the last question."