[Chapter 1790 The victory of mathematics]
The white-haired old Taoist Zhenyang showed a happy expression when he heard the words, and said, “That’s great! Jushi Xia really has a good temperament! There are several problems that have been plaguing Pindao, and the first problem is…”
Speaking of this, Old Taoist Zhenyang shook his head and said, “Today there are pheasant rabbits in the same cage, with thirty-five heads on the top and ninety-four legs on the bottom. May I ask how big are the pheasant rabbits?”
Xia Ruofei suddenly showed a strange look after listening to it, he couldn’t see it!
This old man with thick eyebrows and big eyes is actually a math lover!
No matter how well-written his question was, it wouldn’t change the essence of a mathematical problem!
Isn’t this the original chicken and rabbit cage problem?
The words of Zhenyang Laodao, translated into modern words, are: There are chickens and rabbits in the same cage. There are thirty-five heads on the top and ninety-four feet on the bottom. Ask how many chickens and rabbits each have. Only?
In ancient times, this might have been a very ingenious mathematical problem, but in today’s age, a junior high school student can easily solve it, and it can be solved by composing a binary linear equation. This is also called a problem?
After the old Taoist Zhenyang finished the question, with a smile on his face, he said, “Jushi Xia, you can answer this question with a stick of incense.”
As soon as his words fell, Xiaodaotong Qingfeng had already brought in a prepared incense burner, and a freshly lit incense was inserted into the incense burner.
Xia Ruofei didn’t know whether to laugh or cry, and said directly: “Zhenyang Daoist, don’t have to be so troublesome, I have solved this problem.”
Zhenyang Laodao raised his eyebrows and said, “How could the layman be so fast? Then tell me, what is the answer?”
Xia Ruofei smiled slightly and said, “23 chickens and 12 rabbits, right?”
It is naturally impossible for Zhenyang Laodao to be trapped by a problem. The question he asked Xia Ruofei was actually a test.
Xia Ruofei believed that if other expedition team members including Ling Qingxue would also enter this scene, Zhenyang Laodao would also use the exact same tone and tone to throw the question to them.
As soon as Xia Ruofei said the answer, Zhenyang Laodao couldn’t help raising his eyebrows and said, “This is indeed the answer to this question…”
“So, I have solved this problem?” Xia Ruofei asked with a smile.
“Wait a minute!” said Zhenyang old man, “I want to know, what method did Jushi Xia use to solve it in such a short period of time?”
Xia Ruofei said in his heart: “The two-dimensional linear equation! Can’t you make it directly?”
However, Zhenyang Laodao must not understand binary linear equations. When Xia Ruofei was thinking about how to express the solution in an easy-to-understand way, he suddenly thought of an interesting solution method that he had seen on the Internet before. Although It may seem absurd, but it can be calculated quickly.
So, Xia Ruofei said with a smile: “My method is very simple! Taoist priest, there are thirty-five heads, which means that there are thirty-five chickens and rabbits in total, right?”
Zhenyang Laodao nodded and did not speak, because this is basically nonsense.
Xia Ruofei smiled and continued: “Let both the chicken and the rabbit raise their two feet, then there should be seventy feet missing, right? Twenty-four feet remain from the ninety-four feet, Because chickens only have two feet, after they are raised, the remaining twenty-four feet on the ground are all rabbits. And every rabbit has raised two feet, so they all stand on two feet Twenty-four feet naturally correspond to twelve rabbits. There are thirty-five chickens and rabbits in total. If there are twelve rabbits, naturally there are twenty-three chickens. Isn’t the answer here?”
Old Taoist Zhenyang was stunned, he didn’t expect the answer to be so simple.
After a long while, he said strangely: “How can the chicken and the rabbit raise their feet obediently? Also, the chicken has both feet raised, what kind of posture is this…”
Xia Ruofei almost burst out laughing, he said with a smirk: “Daoist, this is not important, it’s just an assumption! The point is that this method can get the answer the fastest,
isn’t it?
”
Old Taoist Zhenyang thought for a while, and said, “Jushi Xia is talented! This problem-solving method is very ingenious, and the poor Taoist admires it!”
“So, this question has been solved?” Xia Ruofei asked with a smile.
“Of course!” said the old Taoist Zhenyang, “There is still a problem with the poor Taoist, and I hope Jushi Xia will give me some advice.”
“Master, please speak!”
Old Taoist Zhenyang pondered for a moment, and then said, “I don’t know how many things there are. If you count three or three, there are two left, five or five, three, and seven or seven. How many things are there?”
have to!
It is another classic ancient mathematics problem, and it is also from “Sun Tzu’s Suanjing”.
The translation of this question into modern text is: There is a pile of things, three three numbers eventually leave two, five five numbers finally leave three, seven seven numbers finally leave two, find this pile of items quantity.
Xia Ruofei always had a faint smile on his face. This question has a trap. The trap is: the answer to this question is not unique. To be precise, it should be an arithmetic sequence with a difference of 3*5*7.
If the ancients who have not learned much mathematics face this question, they can get the answer by trying numbers one by one, but they are likely to ignore that there are many, many answers to this question. correct.
After the old Taoist Zhenyang asked the question, he looked at Xia Ruofei with a smile.
And Xia Ruofei also looked relaxed, and after a little thought, he said: “Master, the answer to this question is not unique. The number of items in this pile should be at least 23, then 128, and then possibly 233. One, and so on, add 105 to each answer to get a new answer, so there are infinite answers.”
Xia Ruofei’s answer, expressed in mathematics, is 23+105n, where n is an integer greater than or equal to 1.
Xia Ruofei’s answer is very rigorous, it can be said that no water leaks, even if Zhenyang Laodao wants to find flaws, it is impossible to find them.
So, he just pondered for a while, then nodded and said, “The layman is talented! This problem has been solved!”
This time, Zhenyang Laodao didn’t even have the interest to ask Xia Ruofei to explain the calculation method, and directly judged that Xia Ruofei solved the problem successfully.
Soon, the old Taoist Zhenyang continued: “There is one last question, I hope Jushi Xia can also help the old Taoist!”
Xia Ruofei breathed a sigh of relief. He was afraid that this basic math problem would be endless. Although it was not difficult for him at all, it was a waste of time.
Moreover, the test on the first floor of the tower was actually a test of mathematics, which was really unexpected.
Fortunately, the power of setting up these levels is not too bad, and there are only three questions arranged in total.
Therefore, Xia Ruofei has only one idea at this time, that is to end it quickly!
After listening to the words of Zhenyang Laodao, he quickly said: “Daoist, please speak!”
Zhenyang Laodao said sternly: “The last question is quite difficult, but I can only give Xia Jushi a stick of incense. I hope that Xia Jushi can continue to work hard and solve all the problems in one go!”
Xia Ruofei nodded with a smile, and said, “Daoist, please speak, and listen carefully!”
Zhenyang Laodao said, “There are twenty trees today, four in each row. Question: How can I get sixteen rows of trees?”
Xia Ruofei was slightly taken aback when he heard the words, this time Zhenyang Laodao really came up with a worldwide mathematical problem!
However, the challenge of his 16th line is not great, because as early as the 16th century, mathematicians in ancient Greece, ancient Rome and ancient Egypt have completed the 16-line map, and it is widely used in some Western In the decorative pattern of elegant buildings.
But Xia Ruofei thought about it, this secret realm has existed for at least thousands of years, and the sixteen-line map must not have been born at that time, so this question is very difficult. come out correctly drawn.
Fortunately, Xia Ruofei usually dabbles in a wide range, and has really seen this classic mathematical problem.
Therefore, after Xia Ruofei listened to the question, he was also determined, knowing that he would definitely be able to pass this level.
He smiled and said, “Daoist Zhenyang, can you give me a pen and paper?”
Old Taoist Zhenyang thought that Xia Ruofei needed to deduce it, which was normal. Many people used paper to fill a room in order to solve this problem, but they may not be able to solve it.
Therefore, Xia Ruofei can’t deduce directly in his mind, and he still needs to use pen and paper.
Zhenyang Laodao nodded with a smile, motioned to Daotong Qingfeng to fetch the paper and pen, and specially instructed Qingfeng to grind the ink for Xia Ruofei.
Xia Ruofei came to the table, flattened the paper on the table and pressed it with a paperweight, then he picked up the wolf pen, dipped the ink in the inkstone, and began to draw on the paper directly.
A square quickly appeared on the paper, Xia Ruofei marked the four vertices in black, and then precisely marked two points on each side.
After Xia Ruofei entered the Golden Core Stage, his physical fitness has also been improved in an all-round way, and he has a strong mental power and is very good in fine control.
Therefore, he didn’t need a ruler at all, but the square he drew was quite accurate, and each line was straight, as if it were printed.
Then Xia Ruofei connected the two points on each side with the two points on the opposite side and the point on the clockwise side that was far away from them.
Another 24 straight lines, drawn exactly.
In this way, inside the square, an octagon has been formed.
Xia Ruofei smiled slightly, and marked each vertex of the regular octagon formed by intersecting the internal lines of the octagon in black.
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Before the old Taoist Zhenyang could react, Xia Ruofei leaned the brush against the inkstone, and said with a smile: “Daoist Zhenyang, I have finished it!”
Zhenyang Laodao thought that Xia Ruofei was doing drafts and calculations, but he didn’t expect Xia Ruofei to start answering as soon as he came up, and it was completed in such a short period of time. This is just a joke!
Each question gives Xia Ruofei a stick of incense to think and answer, but Xia Ruofei comes up every time to solve the answer without thinking, let alone a question and a stick of incense, after the first three questions are answered, that stick of incense is also Just burned a head off!
Is this done?
Zhenyang Laodao was a little unbelievable, but he glanced at the map drawn by Xia Ruofei, and immediately knew that Xia Ruofei had solved the problem.
Even those cultivators who are proficient in arithmetic, when faced with this problem, usually fall into a long test, and there are very few people who can make it in a single stick of incense.
However, Xia Ruofei completed the answer in just ten seconds, and wrote the answer without hesitation, as if it could be done without thinking at all.
“Daoist Zhenyang, am I right?” Xia Ruofei asked.
Zhenyang Laodao came back to his senses, with a wry smile on his face, and said, “Yes…”
Xia Ruofei said with a smile: “So, I can help you…”
“Of course!” said the old Taoist Zhenyang, “Jushi Xia is indeed very intelligent, and the poor Taoist admires him!”
“Where is it! You are too famous!” Xia Ruofei said with a smile, “Actually, the arrangement of these sixteen lines is not difficult, and I can even arrange a map of 18 lines or even 20 lines!”
“What?” Zhen Yang’s eyes widened when he heard this.
[End of this Chapter]
