Shen Qi took the blank paper handed over by Secretary Liu: "It's okay, I'm a newcomer, so I'll do the questions first to suppress the shock." ”

"Give you 1 hour and I'll go out for dinner. Officer Liu stood up and looked at his watch, it was past five o'clock, and it was almost time for dinner.

"I'm so hungry too. When it came to eating, Shen Qi was indeed hungry.

"If you complete this question within the allotted time and answer it correctly, you will be allowed to eat dinner. Director Liu said expressionlessly, and added: "This is the first rule of the Olympiad national team." ”

"Director Liu, it is not legally permissible for you to treat minors like this!" Shen Qi strongly protested, he was not allowed to eat if he couldn't do the topic, he was so cruel, we are a socialist country with a legal system! This surprise is too shocking to suppress.

"Shen Qi, you are a gold medalist in the mathematics competition, a national champion, not an ordinary minor. Director Liu was not soft-hearted at all, he pointed to all corners of this office of more than 20 square meters: "In the process of solving the problem, you can consult any mathematical literature in this room, many of which are not for sale, and the Chinese Mathematical Society has obtained them through special channels." You should be fortunate that you are swimming in the ocean of knowledge. ”

"I'm a high school student from another place who came to your great capital, and I have no relatives and no friends, what can I do? "Shen Qi has no choice, he is a vulnerable group.

Director Liu left, leaving a cold back.

Shen Qi pulled a chair and sat down, spread the white paper in his hand on the table, and carefully reviewed the topics on the paper.

The first thing that catches your eye is a simple pattern, a straight line running through an ellipse, like a flattened "day".

At 12 o'clock, 3 o'clock, and 9 o'clock in the word "day", y(x), x2, and x1 are marked respectively.

Below is the textual description:

"According to the figure above, the unknown function that appears in the integrand makes the integral extremely large or minimized, and the materialized description is the shape that the rotating surface that moves axially with constant motion to make the motion resistance least resistant, then its mathematical description is?"

The question is not complicated, everyone knows the graphics, and everyone recognizes the Chinese characters, but it can be conservatively estimated that more than 99% of high school students in China do not know, what is this question asking Lao Tzu for?

"Hehe, hehehehe. Shen Qi smiled, like a fool.

He giggled because it was time for dinner.

This question is not difficult, for Shen Qi, one sentence summary is: use mathematical language to describe simple physical motion.

This requires the respondent to have a deep knowledge of mathematics, and the knowledge of physics is enough to be in the scope of compulsory high school textbooks, including Newton's three laws.

Shen Qi replied with a pen and wrote his mathematical description on this A4 blank paper.

The simple point of this question is that Director Liu threw a ball on the surface of the lake, and the ball jumped on the surface of the lake, and finally floated on the surface of the lake, please explain this common phenomenon in mathematical language.

Shen Qi uses Euler's theory of the fastest descent line, that is, the finite sum is used instead of the integral, and the difference quotient is used instead of the derivative in the integrand.

This non-esoteric theory has a wide range of applications, and its function is to make the integral a function of a finite number of coordinates of y(x).

Shen Qi drew an arc on the white paper, a very concise technique.

This operation is not difficult, and engineering students who have taken the test to eighty or ninety points can complete it.

Shen Qi's operation continued, and by making the difference of the integral equal to zero, and using a crude limit process to transform the resulting difference equation, he obtained the conditions that must be met for the minimization of the arc.

Shen Qi's answer was written all over the side of the A4 white paper, and it was done.

Seeing that only 15 minutes had passed, Director Liu had not yet returned, and Shen Qi was idle, so he turned over the A4 blank paper and continued to write.

This time, Shen Qi's operation is a little more complicated, making the points extremely large or minimized, and he does not necessarily have to be a bad quotient.

Euler's method is only an entry-level approach, while Lagrangian's method is advanced.

Shen Qi traced a new moon on a white piece of paper and deduced the endpoint conditions that must be met with a variable endpoint minimization curve, which was a tortuous process.

It took 20 minutes, and Shen Qi gave a second mathematical explanation.

Seeing that there was still time, Shen Qi casually took a new blank piece of paper and began to deduce the third mathematical explanation.

At six twenty o'clock, Shen Qi was really hungry, he put the pen on the table, and opened the zipper of his backpack to find food: "Why hasn't Director Liu returned, eat a chicken leg first." ”

Tearing open the sealed package, Shen Qi ate chicken legs, and he walked around the office while eating.

"This is indeed an ocean of knowledge, there are so many books, some of which you can't see outside the literature. ”

“《Opera-Omnia》，L.Euler…… What the hell is this, an all-English book...... Hey, wait, I seem to know the author, Euler, this is Euler's book...... Damn, I can't read it in English, so I'll change it. ”

"Sister cut you thirsty...... Anna is thirsty...... it, this book is more hanging, the French book is written by ...... Lagrange. Damn, I can't read all French, so I'll change it. ”

"Halo...... There is also a Russian version of the literature...... Liu is an expert in foreign languages? There are few mathematical literature in Chinese in this room. ”

Shen Qi was stunned, Director Liu's office was a sea of mathematical knowledge, but there were few books he could understand, and almost all of Director Liu's collection were references in foreign languages.

Shen Qi was interested in reprints of Euler's and Lagrange's mathematical works, which could not be bought in bookstores or on Taobao unless they were purchased overseas.

However, no matter how interested you are, it is useless to not understand foreign Chinese.

"Isn't it time for me to upgrade my English?" Shen Qi stood in front of a wall of books, nibbling on braised chicken legs, lost in thought.

At this time, Director Liu came back, and he saw that Shen Qi was not immersed in the question but was gnawing on the chicken legs, and he was very dissatisfied: "Shen Qi! Who allowed you to eat chicken legs? On the first day you came to the national team to report, you violated the team rules, and your organizational discipline is too poor!"

"I'm hungry, I'm growing my body, Director Liu!" Shen Qi exclaimed innocently.

Director Liu shouted: "Hunger is not a reason, stupid death is far more tragic than starvation! The chicken leg is thrown away, and you are allowed to eat only after completing the question!"

"Tyrant!" Shen Qi shouted, he reluctantly threw half of the chicken leg into the trash, and muttered in a low voice: "Tyrant, Dark Tyrant......"

"Hey, that's not right! I obviously finished the question that Director Liu came up with, why did I throw away the chicken legs!" Shen Qi suddenly woke up.

"Aren't you done talking about it sooner?" said Mr. Liu, who walked to his desk and looked down at the blank paper with the title written on it.

"I'm starving, I've lost my mind, and I shouldn't have gone to farm the Dark Tyrant at level 5. "Shen Qi squatted on the ground and sulked, this is the chicken leg my dad bought for me, full of fatherly love, damn, I feel sorry for my dad.

"What kind of mess is the Dark Tyrant messy?" Officer Liu frowned and continued to review Shen Qi's answer: "Euler's second-order ordinary differential equations, even if you answer correctly, give this answer within 1 hour, which is decent." ”

"Hmph......" Shen Qi lowered his head and hummed sullenly.

"Why is there a word on the reverse side?" Secretary Liu turned over the white paper, and was surprised for a moment: "Lagrange indefinite integral formula, Shen Qi...... You...... You used two methods to answer my question...... In an hour?"

Director Liu covered his heart with his left hand, and sweat was pouring from his forehead.

"Hmph...... There is also a piece of paper next to it. Shen Qi squatted on the ground, lowered his head, and wrote out of thin air on the ground with his fingers, writing the word "miserable".

"You...... Shen Qi...... You would actually use the Bernoulli divergence series...... You used three ways to answer my question, in ...... In an hour?" Director Liu gasped for breath and couldn't speak.

"Who can be worse than me, only allowed to do questions, not to eat. Shen Qi muttered to himself.

Boom!

There was a muffled sound.

Officer Liu fell to the ground with a bang.

"?" Shen Qi suddenly raised his head and found that Officer Liu was lying on the ground and twitching violently.

"Director Liu, what's wrong with you? You must not die!" Shen Qi rushed to Secretary Liu's side, stunned.

Director Liu's hand trembled and pointed to a corner of the office: "Quick...... Go get it...... Available...... Heart-saving pills...... ...... in the briefcase"