They did it as soon as they said that morning, the two of them roughly determined what materials, colors, and how to match the clothes.

Immediately in the afternoon, Li Zong and Su Ying'er went out to see if there was a suitable cloth in the cloth shop. If you were with you, Xiao Qing would follow you.

In fact, Li Zong had servants around him in the past, but he was a man. Now, with Xiao Qing, he naturally didn't need the one he used to do.

I believe that the other party will definitely blame him in private, but this is also to provide the other party with other ways out. What future does it have to follow him?

As soon as the two entered the cloth shop, the proprietress came up enthusiastically and saw that they did not look like regular customers in the store, but they were quite married.

The boss's wife, Qi Niang, understood immediately, "Welcome, please, the couple are here to buy cloth? Our place is definitely the largest cloth shop in the county. If we don't have it here, there will definitely be no other place."

As soon as he came up, he was directly identified as a couple. This made Su Yinger a little uncomfortable and became a little more shy, but Li Zong was much calmer.

He just replied: "Well, take out all the cloth and take a look."

...

Then, when Zhang Gongchuo and Hengxun arrived, they found out that Li Zong had gone out, but because they were going out to buy cloth, it probably wouldn't take long.

So the two of them were waiting for tea in the mansion. Seeing that the atmosphere was quite awkward, Ning Bo also came forward to chat and soon learned about their identities.

Actually... there is nothing to hide, but when I learned about the identities of the two, I still felt a little incredible.

"My Goro has always been very casual, so if you have any bad hospitality, please don't be surprised."

Heng Xun felt it was indifferent and said, "Butler Ning is so serious. It should be said that we are here to disturb Wulang's purity."

"Speaking of this... Goro has married?"

Uncle Ning sat down and said, "It's about ten days ago."

Heng Xun: "The woman from the He family?"

Ning Bo said: "Sanniang from the magistrate's family in Su County, Yanlan County is also a very famous talented girl in this area."

Heng Xun: "So that's the case, it's a pity."

Zhang Gongchuo: "What are you saying?"

Hengxun said, "I mean, it's a pity that I missed a good opportunity. But I think I don't have any other nieces of the right age, so I'm just talking about it. Speaking of which... Is your Goro born so smart? Why are you so unfamiliar before?"

Ning Bo also said: "How to say this? Because five years ago, Goro had a serious illness and had been at home for many years. He had never even gone to the academy. Naturally, he had less contact with outsiders, and people outside knew very little about Goro."

At this time, Zhang Gongchuo also said: "With Wulang's talent, I went to the Imperial Academy to teach and teach, and I think there is no problem."

This surprised Ning Bo a little. Wolou was comparable to a bachelor's degree.

This is too high to lift Goro.

...

After a while, Li Zong finally came back with Ying'er, and the three of them stopped talking.

Of course, after entering the door, Li Zong and Ying'er left separately, but Li Zong came to the hall alone.

Seeing that the two had been waiting for a long time, they also said, "If you have something to do when you go out today, I will ask Uncle Ning to entertain the two of you first. The two old gentlemen have been waiting for a long time."

"It took only a short while, and I sat there for a while."

"Can we talk about the equation of pi this afternoon?"

Li Zong paused with his forehead and continued, "It can be said that, but it is less than pi."

After sitting down, Li Zong also drew a horizontal coordinate and a vertical coordinate.

He said: "Today, let's talk about the coordinate system first."

Coordinate system...

Another word that two people have never heard of.

Li Zong grind the ink and spoke, "What is a coordinate system? It means drawing two straight lines, and these two straight lines must be perpendicular to each other."

"The so-called vertical is right angle."

Soon the ink was ground, and then Li Zong suddenly asked the two of them: "Have you ever seen a kind of black stone produced, with a shiny texture and should be a little soft to the touch."

Although the two of them didn't know why Li Zong asked this, they replied: "Are you talking about coal?"

Li Zong: "No, not coal, the surface of coal is not shiny. It's something similar to coal."

"I wonder what the use of this thing is for me?"

Li Zong: "It's okay, just ask, forget it, let's continue to talk about the coordinate system. The coordinate system I mentioned to you looks like this!"

Draw it, then spread it out for the two of you to show it.

"The horizontal one is the x-axis, and the vertical one is the y-axis. Then, whether it is before the x-axis or the y-axis, there are some very small scales, such as this small segment, which represents 1, and then here, there is another small segment, which is 2. In this way, the x-axis can be divided into many, many segments, 1, 2, 3, 4... all the way to endless."

"And, the same is true on the y-axis side."

"We all know that circles have shapes, and when we place the circle on this axis..."

"Will you just list a formula related to this circle?"

"Suppose that the radius of the circle is one-half, set the center of the circle at this position of (1/2,0) of the coordinate axis."

"The way to read the coordinate axis is to read the x-axis first, then the y-axis. Moreover, the two numbers x and y determine the position of the point, just like (2,3), which means two x-axis and three y-axis. Then the coordinate of (2,3) means that it is here!"

Li Zong pointed a dot on the paper and put the note next to it (2,3).

"The problem now is, if I know all this, then this circle should be represented by x and y."

This time, because Li Zong spoke more and more, Heng Xun was a little confused at once. And it was Zhang Gongchuo who looked confused when he first saw this thing. However, from the first sight of him, Zhang Gongchuo understood the function of this thing. Li Zong planned to use the coordinate axis to represent this circle.

But can this be expressed?

Zhang Gongchuo's heart began to beat faster without any competing.

It may be a bit difficult to set the center coordinates at (1/2,0) from the beginning, so next, Li Zong changed another coordinate system and set the center of the circle at (0,0).

"If so! How to use an equation to represent all points on this circle."

"For example, when x=0, y is equal to what. Assuming that the radius of this circle is 1, then is y equal to 1."

"Then the question is, it's just a point, if I want to represent all the points here!"

"Think of the edges of the circle as lines connected by countless small dots."

"So……"

"What relationship should x and y satisfy? This formula is not as simple as chickens and rabbits in the same cage."

Heng Xunxin said: "You can tell! This is not just as simple as chickens and rabbits in the same cage. I almost fainted from my head. My brain hurts a little."

However, this opened up a new world for Zhang Gongchuo, that is, the world of geometric figures and algebraic formulas.

Li Zong gave him a very magical feeling.

That is—
Chapter completed!