"Li sacrificial wine, forget the problem, today I came here to ask you some questions about that lens, that day I saw my aunt give my grandfather a pair of reading glasses, so that he can see things near clearly, what is the reason?" Li Chengdao was not interested in Li Xiu's suggestion to let him solve arithmetic problems, after all, in his opinion, Qi Niang, who was a few years younger than him, would definitely only do some elementary problems, and there was nothing to calculate at all, and the question of reading glasses interested him more. Pen × fun × Pavilion www. ｂｉｑｕｇｅ。 ｉｎｆｏ

"Hehe, the principle of reading glasses can't be explained clearly in one or two sentences, if you want to completely understand the principle, you must have an extremely advanced arithmetic foundation, so the king of the county should go and solve that problem!" Li Xiu said with a light smile, the principle of reading glasses seems simple, but it is an optical problem in physics, and it also involves the calculation of light refraction and other aspects, so Li Xiu is not wrong to say that he needs a mathematical foundation.

Hearing Li Xiu say this, Li Chengdao was also a little skeptical, and then Princess Pingyang said with a serious face: "Dao'er, since you want to come to Li Xijiu to ask for advice, you have to obey Li Xijiu's arrangement, otherwise you might as well go back to the palace and learn from a few masters!" ”

"Yes, my nephew understands!" Li Chengdao finally came to his senses when he heard his aunt's words, and after speaking, he saluted Li Xiu again and said, "Chengdao was a little confused just now, and I hope that Li Xianjiu will not be blamed, I will solve the problem!" ”

Li Chengdao was just about to go to the pavilion after speaking, but at this time, Princess Pingyang spoke again: "Dao'er, since you have asked Li Xianjiu for advice, although you don't have a real apprenticeship, you can't be too rusty, I think you call Li Xianjiu Mr., Li Xianjiu doesn't have to be too polite with Dao'er, just call him by his name!" ”

"What my aunt said is very true, I will meet Mr. Chengdao!" Li Chengdao was extremely clever, and when he heard this, he immediately changed his name and saluted Li Xiu, speaking of which, his grandfather Li Yuan only agreed to let him ask Li Xiu for advice, but did not let Li Xiu be his teacher, so it was very appropriate to call Li Xiu "sir".

Princess Pingyang said so, Li Xiu couldn't refuse anymore, and he always wanted to call Li Chengdao, a little kid, the king of the county, and he also felt a little uncomfortable, so he also responded casually at this time: "You don't have to be polite!" ”

Seeing Li Xiu agree, Li Chengdao was also very happy at the moment, and then he saluted again and left, and came to the pavilion to read the topic. Qi Niang was lying on the table biting the head of the brush, with a tangled expression, after Li Chengdao came in, she just glanced at him, and then continued to bite the tip of the pen, this question is still a little difficult for her, and she has not sorted out her thoughts for the time being.

Looking at Qi Niang's tangled expression, Li Chengdao smiled calmly, he was quite confident in his arithmetic, after all, he didn't think that Li Xiu would give a child like Qi Niang any problems. However, the smile on Li Chengdao's face didn't last long, and when he saw the question in front of Qi Niang, he was stunned for a moment, because he couldn't understand this question, to be exact, there were some things that looked like ghost talismans that he didn't know at all, and the others could be understood.

Li Chengdao never expected that he couldn't even read the topic, and wanted to go back and ask Li Xiu, but he saw that he and his aunt seemed to be chatting very happily, and he couldn't even understand the topic, which really made him feel very faceless, and he was embarrassed to ask Li Xiu, which also made him also show a tangled expression.

But soon Li Chengdao found a turning point in things, because he saw that the draft in front of Qi Niang had a lot of the same symbols written on it, which meant that she must know it, so he finally asked cheekily and softly: "Little sister, what do those symbols on the title mean?" ”

Qi Niang was thinking about the key to this question, and was suddenly interrupted by Li Chengdao, who was very unhappy, and immediately glanced at him and said, "Haven't you played cards?" ”

"Solitaire? I seem to have heard of it, but haven't played it? Li Chengdao was also a little embarrassed at this time, because when Qi Niang spoke, it seemed that everyone should be able to play cards.

"It's pathetic, I can't even play cards!" Qi Niang glanced at Li Chengdao with some sympathy when she heard this, and then picked up the brush and wrote ten Arabic numerals on the paper, as well as the corresponding Chinese characters, "Okay, you can see for yourself, if there is anything you don't understand, ask again." ”

It was the first time that Li Chengdao was said that he was pitiful, and the other party was still a girl a few years younger than him, which made him blush, and he didn't even dare to look at Qi Niang, so he had to stare at the numbers on the paper, and then memorize them one by one in his heart.

Li Chengdao originally had a mathematical foundation, and he was extremely smart, so after knowing ten number symbols, he asked Qi Niang about the law of number arrangement, and soon understood the meaning of the question, but the question was understood, but he had a little bitter smile on his face again, because he couldn't solve this problem.

Ancient Chinese mathematics is also very developed, even the circularity can be calculated early, but the ancients attached far less importance to arithmetic than literature, although there are also arithmetic subjects in the imperial examination, but it certainly cannot be compared with Jinshi and the first, even if the emperor and grandson like Li Chengdao, the main energy is also on the education of Confucian classics, as well as current politics, and only learned a foundation for arithmetic, as for the unary equation in front of him, he really doesn't know how to solve it?

Li Chengdao didn't understand, Qi Niang's eyes suddenly lit up at this time, she finally thought of the key to this truth, and began to calculate it seriously on the paper, and finally got a correct result, in order to ensure that it was correct, Qi Niang also checked it several times, and finally determined that this was the correct answer.

Li Xiu took a look at Qi Niang's calculation process, and found that although she did not substitute an unknown, she used another more cumbersome method to solve this problem, which is also very good, and he couldn't help but praise Qi Niang at the moment: "Not bad, Qi Niang, you are indeed very smart, but don't be proud, because there are more simple ways to solve this problem." ”

As soon as Li Xiu's words fell, I saw Li Chengdao also walking over dejectedly at this time and said, "Mr. Qiyu, I can't solve this problem!" ”

Princess Pingyang saw that Li Chengdao actually admitted defeat, but Qi Niang solved it, and she was also very curious at the moment, and took the topic in Li Xiu's hand and looked at it, but her long eyebrows also wrinkled suddenly, because even she felt a little difficult to solve this problem, and she thought hard for a moment before coming up with a solution.

"Li sacrificial wine, isn't it too early for Dao'er to let them do such a difficult topic?" Princess Pingyang said softly at this time, she felt that maybe it would be more suitable for Li Chengdao to do such a topic when he was a few years older.

"Princess, this is actually a very basic topic, and its solution is actually very simple, I want to teach Qi Niang them now, you can understand it by looking at it!" Li Xiu said with a smile, if this problem is solved with traditional thinking, it is indeed very troublesome, but if you list a one-dimensional equation, it becomes extremely simple.

Li Xiu picked up the pen as he spoke, and then began to list the equations on the paper, and then wrote the solution again, and the result was obtained in two very simple steps, which also made Princess Pingyang and Qi Niang and others all a little dumbfounded, but at this time Princess Pingyang raised her own question: "Li Xijiu, what does the fork you drew mean, and what do those crosses and two horizontal lines mean?" ”

Although Princess Pingyang knows Arabic numerals, she doesn't know the meaning of the calculation symbols, so she can only see that the result is correct, but she can't understand the process of calculation, and the same is true of Li Chengdao next to her, Li Xiu also patiently explained it, this thing is very simple in the eyes of later generations, that is because the education of later generations has already laid a solid foundation, and now Li Xiu wants to explain to Princess Pingyang and Li Chengdao, who have no foundation, and it has taken a lot of time.

It was not until noon that Princess Pingyang and Li Chengdao finally understood Li Xiu's problem-solving process, and finally Li Xiu concluded: "This problem is actually a standard one-dimensional one-dimensional equation, and when you encounter similar problems in the future, you can substitute an unknown number to solve it, and this is also the most basic, and there will be a one-dimensional quadratic equation in the future, a two-dimensional quadratic equation, etc., although it is more difficult, but it is developed on the basis of this one-dimensional equation!" ”

"I see, I didn't expect arithmetic to be able to learn like this!" Princess Pingyang also sighed with emotion after listening to it, Li Xiu's arithmetic ideas are completely different from those she learned before, and after adding various symbols, the whole problem-solving process is more simple and clear, and the dispatch of grain and grass materials in the army also needs to be calculated.

"Mr. is talented, Chengdao can follow Mr. to study, it is really a blessing for Chengdao!" Li Chengdao was also convinced at this time, just one arithmetic made him see the talent in Li Xiu's chest, and he was sure that these were just the tip of Li Xiu's talent, and there must be something more amazing in his chest.

"Hehe, these are nothing at all, just some basic things!" Hearing Li Chengdao's words, Li Xiu couldn't help but smile and said, he originally deliberately shocked Li Chengdao, lest he disobey discipline, presumably after this incident, he should have respect for himself, which will also facilitate his management in the future.

"Brother, don't say it again, I'm almost hungry!" At this time, Qi Niang was a little dissatisfied, she had been laid some foundations by Li Xiu before, so she had already understood the solution to this problem, and the time had already passed noon, Liu Er had come to see them several times just now, just because Li Xiu was lecturing, so she didn't interrupt them, and it is estimated that lunch has been hot a few times now.

Hearing Qi Niang's words, Li Xiu and Princess Pingyang couldn't help laughing. In the next period of time, Li Xiu would give lectures to Qi Niang every day, Li Chengdao would come to listen to the lectures as long as he was free, but the courses that fell in the middle could not be made up, and in the end, I don't know how he bribed Qi Niang, and asked her to help him take notes, and every day Princess Pingyang sent someone to the East Palace to Li Chengdao, so that he would not fall too far behind in the course.

But just a month later, when Li Chengdao came to Li Xiu to listen to the class, he suddenly brought one more person! (To be continued.) )