my scientific age

Chapter 39: A Taste of Coca-Cola in 1937
Hua Luogeng stared at the answering process of the second sub-question given by the blackboard, and nodded involuntarily, and looked at Yu Hua, whose eyes were full of sweat, with a look of approval in his eyes, without urging him to do the third sub-question quickly.

Now, in Hua Luogeng's mind, Yu Hua, who can finish the second sub-question in one breath, has been rated as an excellent mathematical seedling, with excellent mathematical talent, a very solid grasp of basic knowledge, and a very solid foundation.

However, the strange thing is, why Yu Hua can do this question, but Zhao Anyuan, who is the first in the ranking, can't?

After taking a short rest for 20 seconds, Yu Hua didn't delay anymore, and turned his eyes to the blackboard again, ready to overcome the last difficulty in front of him in one go.

The most difficult part of the whole function question is the third sub-question in front of him, which is also the part of the content that Yu Hua has not yet fully understood.

Take a deep breath, adjust the state, hold the chalk, and write again.

(3)

f'(x)=e+txe-e=e[1+tx-e(1-t)x]≤e...

当t≤1/2，且x＞0时，有f＇（x）=e［1+tx-e（1-t）x］≤e……

1+x-e＜0，也有1+x/2-e x/2＜0，故f＇（x）＜0，所以函数f（x）在（0，+∞）内单调递减；

当1/2＜t＜1时，0＜1-t＜1/2，且t/1-t＞1，

After writing the mathematical formula and steps, Yu Hua stopped, his brows furrowed, his eyes fixed on the blackboard, he found that he still couldn't figure out the third sub-question.

Seeing Yu Hua paused, everyone in the classroom followed the changes, their breathing stagnated, and their eyes were all focused on Yu Hua.

Can't figure it out?

Fang Yu's eyes were a little disappointed, and she thought silently in her heart. She didn't mean any jealousy, only regret. It always made people feel that something was missing.

Come on, Yu Hua!
Zhou Yuan clenched his right hand silently, and in his heart, he cheered for his fellow tablemate who was as high as the sky.

An invisible and solemn atmosphere permeated all around.

silence.

Dead silence.

Time passed, and after half a minute, Yu Hua, who was facing the blackboard, shook his head slightly, sighed, and prepared to put down the chalk and apologize to Hua Luogeng.

"Take x=1, when t≥1, it contradicts the known." At this moment, a calm and recognizable voice came over, which was a reminder from Mr. Hua Luogeng.

The voice was smooth and clear, reaching Yu Hua's ears.

contradiction?

Contradicts with known?
Suddenly, Yu Hua, who was about to give up, froze in place, and his mind exploded like an explosion, leaving a blank space. Then, the whole person seemed to have broken through the shackles and understood the situation in the third sub-question, countless mathematics. Symbols and formulas flow, arranged according to extremely strict rules.

He figured it out.

"Squeak!" A sharp and harsh rubbing sound came out, and the chalk swiped on the surface of the blackboard, sketching out beautiful and elegant mathematical symbols.

Yu Hua seemed to be enchanted, his eyes fixed on the blackboard, and his right hand was writing extremely fast.

"Let h(x)=1+tx-e(1-t), then h(0)=0, h'(x)=(1-t)[t/1-te(1-t)x] , when 0<x<1/1-t Ln t/1-t, h'(x)>0, so h(x) is monotonic in (0, 1/1-t Ln t/1-t) Descending, so h(x)>h(0)=0, at this time f'(x)>0, so the function f(x)>f(0)=0, which is inconsistent with the title. In summary, if and only When t ≤ 1/2, the function f(x) is a decreasing function within (0, +∞)."

With sweat on his forehead, Yu Hua became more and more excited as he wrote. He only had the blackboard and mathematical characters in his eyes, and nothing else. While writing, he even read it out.

After 1 minute, the sound of chalk writing on the blackboard surface disappeared.

There was silence in the classroom.

"Papapa!" In the next second, there was a sudden applause in the classroom. This was the applause from all the students in the first class of Science, not for anything else, but for Yu Hua who made the question.

Yu Hua almost single-handedly completed this extremely difficult function problem.

"It's a top-notch math seedling." Hua Luogeng smiled and applauded Yu Hua on the podium with both hands. He was very impressed, and his evaluation took it to a higher level.

The dusty right hand wiped the sweat from his forehead and looked at the blackboard. He stood on the spot with an imperceptible arc on the corner of his mouth. At this moment, Yu Hua, who was enjoying the applause of his classmates, felt an overwhelming sense of accomplishment. I solved this problem face to face with the whole class. This feeling is more refreshing than drinking a bottle of Ice Kuoluo in dog days.

When you have the money, be sure to try Coca-Cola from 1937.

"Sir, Yu Hua has solved it, thank you for your advice." Yu Hua didn't get too complacent, put down the chalk, turned around, and said respectfully to Hua Luogeng.

Hua Luogeng smiled and said, "You don't need to thank me. If you want to thank me, thank yourself. It's all right. That's right. Let's go down first."

"Yes."

Yu Hua respectfully said goodbye to Hua Luogeng, turned around and walked off the podium. He felt a famous student staring directly at him. When passing the first row, top students such as Zhao Anyuan, Fang Yu, Li Fan and others all gave their thumbs up.

Yu Hua grinned at the crowd, returned to his seat and sat down under everyone's attention.

"Awesome! It's amazing! You really shocked the audience today, and shocked everyone." After Yu Hua just sat down, Zhou Yuan gave a thumbs up and whispered in admiration.

"Class, class." Hearing Zhou Yuan's praise, Yu Hua smiled and had to say that this feeling was really comfortable.

On the podium, Hua Luogeng came back to the center of the podium and said to everyone, "Yu Hua's answer is very correct, have you ever understood?"

understand?

Except for a few top students in the first row who barely understood it, the rest of the crowd blinked, bewildered.

Although I watched Yu Hua's problem-solving process, there was still no change in the nature of the problem in front of me, and it was still in a state of incomprehension.

Just read it once and understand?
joke.

Sir, you really think too much of my IQ.

"If you don't understand, copy it down and study it after class. I have three function questions in total. The difficulty is easy, normal, and medium. You should raise your hands on the first question, only a few people will raise your hands on the second question, and the third question. Only Yu Hua raised his hand. That’s how many functions change. Functions include derivatives, and derivatives are micro-quotes. From micro-quotes, there are both differential and integral. If you want to get into a university, you can do some scientific research in the future. , be sure to learn the basics of functions.”

Hua Luogeng felt the helpless eyes of everyone, smiled, and explained slowly: "Do you understand?"

Function is one of the basic knowledge. Hua Luogeng tested everyone through three questions, with only one purpose, so that they can truly understand the importance and significance of arithmetic.

If you want to work in science and science, you cannot do without a solid mathematical foundation.

don't count?

How to get the parameters such as the ballistic trajectory and velocity variables of the projectile?
How do planes fly at high speeds?
How are the air velocity and variation data on the fuselage surface derived?

If you don't know how to calculate, the road of scientific research is really difficult.

"I'll understand, thank you for your teaching." All the students stood up and said respectfully.

Looking at Hua Luogeng on the podium, Yu Hua's eyes were full of respect.

"Boom! Boom! Boom!" The next moment, the bell rang, representing the end of the first lesson. It was low and distant, with penetrating power, and spread all over the four middle schools.

Hearing the bell from outside the classroom, Hua Luogeng smiled, walked off the podium and left the classroom under the bow of a student from the first class of name and science.

The first class of school is over.

Today, Peiping No. [-] Middle School not only welcomed Hua Luogeng, a mathematics professor from National Tsinghua University, but also the next-door literature class welcomed Chen Yinke, Wen Yiduo, Feng Youlan and other well-known National Tsinghua professors to teach the first class in person.

(End of this chapter)