From the very beginning of high school, many students wonder why we should learn parabola, why we should start with this weird thing.

In China, 9o% of students will not know the answer from birth to death. Some people may not even think about it, and some people may think about it and don't get a satisfactory answer. As a result, generations of Chinese students have studied parabola with doubts in their minds, thinking that this is the simplest figure in the world.

It's certainly not the easiest graphic in the world, it's surprisingly difficult, it takes countless genius brain cells, it's just too much studied and it's just plain simple.

Students start with parabolas in order to learn about conic curves, from circles, parabolas, ellipses, and hyperbolas -- all of high school math -- all about the same problem: conic curves.

Descartes' work was perhaps the culprit in bringing conic curves into all schools, in his coordinate system, images of binary quadratic equations could represent conic curves, and all conic curves were elicited in this way, thus creating a close connection between geometry and algebra. However, this is not possible in all coordinate systems, and scholars have simply chosen the simplest and most orthodox way and put it in textbooks.

The orthodox and simple model of education makes sense in many cases, for example, for the crossing of the congregation.

Even if cheating was used in all the exams, Cheng Jinzhou could still name the characteristics of dozens or hundreds of conic curves without panting, but he obviously couldn't do that.

Cheng Jinzhou turned around and looked at the contents of the whiteboard seriously, pretending to be thinking, but in essence, he was judging the depth of research of several star warlocks.

The earliest study of conic curves was about a little later than Euclidean's, also before 2ooo BC, and then, like Euclidean geometry, fell into a silence of 1ooo years, then recovered, then died, then defrauded, then suspended animation, and finally was completely destroyed by Descartes......

As a necessity before analytic geometry, conic curves were also well studied in the Great Xia Dynasty, especially the application of ellipses in astronomy, which was almost fatal to the attraction of astromagicians. Cheng Jinzhou said while judging: "I think the research on the ellipse is very sufficient, and it is also an important part. ”

Liu Kuang said with a very pious look: "Since the five-star warlock of Gao Muen, the flexibility of the star warlock in the air has been greatly improved, and now the star warlock who can fight in the sky has a unique study of the ellipse, and of course, the triangle is also an indispensable content. ”

Cheng Jinzhou listened to it with a hard time. The five-star warlock requires 1o million Covenant points, which is equivalent to 1o million people using his research results, which is definitely a remarkable achievement. In the entire decade after the 21st century, the most cited single paper (Note 1) was an American chemistry paper, which was cited only more than 7ooo times, and the number of citations in the whole Chinese paper in the past 1o years was only more than 26o million times.

Looking at Lu Xu with a convincing face, this Gao Muen five-star warlock is probably a well-known legend, and Cheng Jinzhou is not good at asking him for details so as not to reveal his stuffing, so he pretended to understand, organized his language, and said slowly: "Regarding the ellipse, I know that it uses a plane perpendicular to the cone axis to cut the cone, and what is obtained is a circle, and the plane is gradually tilted, and what is obtained is an ellipse, and it still has a focus...... Uh, it should be possible to express it in a formula. ”

He deliberately said it like he was talking about a field that he was not familiar with.

"Do you know how Focus works? And the formula expression of the ellipse? ”

"I just know some, the specific content ......" Cheng Jinzhou spread his hand and smiled embarrassedly.

Liu Kuang's question is certainly not difficult, but the conceptual formula must be simplified and special, and not necessarily exactly the same as what the star warlocks understand. Just like Euclidean geometry, the conic curves that high school students learn and the theorems and formulas they learn have been improved for more than a thousand years, and it is natural that there are different ways to express them.

Although it was just two simple sentences, Liu Kuang nodded with satisfaction and said: "From plane geometry to dynamic geometry, it is indeed not easy, which shows that you are also very serious about reading, will there be any reading now?" ”

The books of the Astral Warlocks were still circulating among the nobility, but they were never comprehensive.

Cheng Jinzhou is a o, he used to say that he was self-taught, but he did not prepare relevant books, fortunately, Liu Kuang didn't care, otherwise it would be another trouble.

Not wanting to talk about things that would be easy to show his feet, he just nodded quickly and said, "It's okay, so I can take your airship?" When will it come out? ”

"When do you want to come out?" Wang Linghe smiled kindly.

"It's best to arrive in the capital within half a month."

If it is a fast carriage, it will take about 2o days to get to the capital, and the so-called long night dreams are many, and it is naturally better to arrive early.

"Then let's go to sunrise after tomorrow, we've been away long enough." Liu Kuang agreed, hooked his fingers outward, and saw an attendant walking over with a stack of books.

There are four books in total, all of which are hand-copied, but the paper is very good, and the white color is far from the color that can be bought in bookstores, and it looks more like a printed copy from the Republic of China, which is definitely a rarity in the Great Xia Dynasty.

"4 books, all about ellipses and parabolas." Liu Kuang took the book in his hand and handed it to Cheng Jinzhou: "If you are sure of the imperial examination, let's read more books about star warlocks." ”

At any time on this planet, astral warlocks are limited, and there are even fewer astral warlocks who can show off in theory, and when Liu Kuang determined Cheng Jinzhou's potential, some overtures were inevitable, such as flying tickets, book gifts, and airships.

Cheng Jinzhou politely opened the book, it turned out to be a standard essay mode, such a book must be a boring type. Since he was in college, he has been forced to read by his parents, but he didn't expect to come to the other world is no exception. Of course, the content of the book is very useful, at least to have a systematic understanding of the study of conic curves in the Great Xia Dynasty, and in addition, you can remember many symbolic applications, but with the momentum of a lazy person holding up the four books, Cheng Jinzhou is a bit of a numb scalp.

Reading this kind of book, it seems that it will always be described as gnawing.

"Let's go on, you can read the book, you can listen to it." Liu Kuang stood up with a smile and returned to the whiteboard. The same is true for Wang Linghe and Xiang Xin.

Cheng Jinzhou's eyes widened, not knowing when he fell into the group of hardworking people again.

The wind was blowing in the sky above the courtyard, and the courtyard was still warm as spring, and the atmosphere inside was surprisingly harmonious. Cheng Jinzhou was a little afraid to face the sadness of his parents, so he didn't say goodbye at all, half reading books, half watching a group of people waiting on the whiteboard to write and draw.

Xiang Xin and Liu Kuang are masters and apprentices, Wang Linghe is Liu Kuang's junior brother, the three of them are on the whiteboard, talking and writing, and the discussion is very much like a brainstorming in later generations. In the academic world he understands, there are very few such face-to-face discussions, and it is becoming more and more difficult for researchers to detach themselves from computers, and the size of computers is getting bigger and bigger, even in theoretical physics, it is difficult for people to express their thoughts with two blank sheets of paper. In fact, most of the scientists who participated in the conference still mainly read the conference records, and few people could understand it thoroughly on the spot.

Cheng Jinzhou didn't participate in it, but listened quietly, pretending to know a little about the conic curve, which made Xiang Xinxing Warlock feel very happy. With the qualifications of a first-class star warlock, he was educated by a young boy all day long, even if he recognized the talent of the other party, there would still be occasional depression.

Lu Xu, like Cheng Jinzhou, held a teacup and listened. He is a pure battle star warlock - the burden of star arrays on the human body is very large, and only a very small number of people can etch more than 4 star arrays, and for such people, the requirements will naturally be lowered accordingly.

However, in Cheng Jinzhou's opinion, the requirements for Mr. Lu Xu are too low, so that he can't even reach the level of ordinary people, and the star array he uses is completely designed for battle, which is quite inferior to the flexibility of a serious star warlock.

Just when Cheng Jinzhou shifted his attention to the whiteboard, Mr. Customer Service jumped out without warning, and said seriously: "There is still a 24-hour deadline before the loan period expires, and if you do not repay it within the time limit, you will recover the principal on the premise of deducting the mortgage contribution points." ”

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Note 1: The number of citations in a paper refers to the direct use of the paper's conclusions when someone presents a new paper. It is equivalent to acknowledging the results of the paper and showing that it is influential and useful in the field. At the same time, there are certain requirements for the table journals that cite papers.

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