After Dong Lanyu begged and begged, Xu Lingchu reluctantly agreed to perform an English play together at the English Festival.

But she was sitting at the window chatting, looking back at the other girls in the class, and couldn't help but say: "Lan Yu, it's useless for me to promise you. No one in the class is willing to perform an English drama with us. What can we perform with just the two of us?"

?”

Dong Lanyu followed Xu Lingchu's gaze and saw that the other girls in the class were gathered together and chatting about their favorite popular young meat. The only exception was the two of them, who seemed to be isolated.

It is common for girls to fall into different circles. The reason may be a little jealousy or jealousy. Xu Lingchu had many suitors, and if he couldn't stand it, he would alienate and reject them.

Because art students do not have high requirements for cultural achievements, many students come to art classes only after they failed the high school entrance examination. The students in the class also have connections with their families and do not worry about the future.

Xu Lingchu took the initiative to sign up for art classes because he liked music. Whether it was cultural classes or art classes, he was always the first in the class, and he was a bit different.

People are divided into groups, and people like to get along with similar people.

Of course, Xu Lingchu is not considered a top student. At best, she is short and top-notch. She does not focus entirely on her studies. She usually pays attention to her appearance. She knows how to dress up better than other girls in the class. Her facial features are lifelike and she is exquisite and good-looking.

, and I know how to dress well, so I look very beautiful.

At this time, they found Xu Lingchu and Dong Lanyu looking at them, and the girls in the class cast disdainful looks.

"Girls have a lot of things to do. They are such jealous creatures..." Dong Lanyu curled his lips, feeling that they were jealous of Xu Lingchu's cleverness.

Xu Lingchu paused, turned his head, couldn't help laughing, and scolded, "What, idiot, you are also scolding me, as if you are not a girl!"

"I don't think I'm a man."

"I can't tell you're a boy. Are your breasts so big because they're padded?"

"Bah, bah, what are you talking about? I mean a tomboy. Look, my flirting skills are perfect. I can make you happy with just a few strokes. Hey, why was I born a girl... Forget it, I hate it.

Everlasting." Dong Lanyu couldn't help but sigh, turned to look at Xu Lingchu, and whispered, "Lingchu, when I think of you abandoning me and playing with Li Xuan, I want to cry."

Xu Lingchu blushed and bit his lip: "Lan Yu, I'll get angry if you keep talking nonsense..."

Dong Lanyu laughed again after hearing this. She felt that she liked Xu Lingchu if he was good-looking, with a good-looking skin and an interesting soul. In comparison, she found that she still liked the good-looking skin more, which was quite superficial.

In the same high school, we just met by chance. Now it would be exaggerated to say that a good relationship is better than a good relationship, but she just likes to be with Xu Lingchu.

"Why don't we find boys to join us? If we don't have an English drama together at the English Festival, I always feel like there's something missing in high school." Dong Lanyu added.

"Forget it." Xu Lingchu pursed her lips and smiled. English dramas are nothing, and she doesn't want to care about the people who isolate her. Others say that if you are isolated, you should look for reasons from yourself, but she is not very good at finding reasons, let alone

Too lazy to resolve conflicts among classmates.

She doesn't want to make friends and drag her down, and she doesn't care. She just misses her junior high school friends a little bit.

…

…

After Xu Jiayi returned the gold medal to Li Xuan, Li Xuan put it away.

He also found that Xu Jiayi talked a lot less than usual. After giving him the gold medal, she stopped talking and started immersing herself in homework. The same thing happened in the morning reading class. She came earlier than anyone else and did her best to endorse things.

Xu Jiayi had been acting a little abnormal recently. Li Xuan thought for a while and didn't know why, so he just assumed that Xu Jiayi suddenly wanted to study.

Even though she was quite stupid, Li Xuan saw her struggling with a math problem for a long time. However, when Li Xuan was about to explain it to Xu Jiayi, he was ruthlessly rejected by Xu Jiayi.

"I'd better think about it myself."

Xu Jiayi said this with her head lowered, looking willful and stubborn.

Li Xuan thought to himself that he was really a bit mean. In the past, people kept asking him questions, and he was actually a little annoyed deep down in his heart. But now that others stopped asking, he took the initiative to get involved.

Li Xuan still ignored her and did not disturb Xu Jiayi's study.

…

…

During evening self-study, Li Xuan went to the math competition group as usual.

In the current high school mathematics competition group, if there are classes, most of the time students write math competition questions by themselves, but there is something different today. Many students in the competition group saw Li Xuan coming and joined in enthusiastically.

"Master, how do you solve this problem?" A classmate asked Li Xuan a question.

"..." Li Xuan always felt something was strange, but he still read the title.

The question is very simple, it is like this: There is a well, seven meters deep, and a snail climbs up from the bottom of the well. It climbs three meters during the day and falls two meters at night. How many days does it take for the snail to climb out from the bottom of the well?

Why does a snail fall two meters at night?

Of course, this is not the point. Li Xuan no longer pays attention to this strange place.

Seeing this question, Li Xuan thought for a moment but did not answer immediately: "What do you think about it?"

The classmate said: "Five days. Climb three meters during the day and drop two meters at night. One day is a climb of one meter. The well is seven meters deep in total. If the final climb is three meters during the day, then the number of days ahead is exactly four meters, so

That’s four days. Four days plus one is five days.”

"I think so too."

Other students who were watching also echoed.

Liang Zhihui saw many people asking questions around Li Xuan, and came over very curiously. When he saw this question, he was slightly stunned.

"That's no problem." Li Xuan was surprised. He also thought it was five days.

"But the answer is six days."

Li Xuan: "…………" This is very embarrassing.

The classmates around me started talking all over the place: "Why?" "Yes, why is that?" "I think it's five days." "I think so too."

Li Xuan didn't understand either. He looked at the question and immediately saw the key point. He understood: "I understand. Maybe the question means to climb out of the wellhead, and you can only climb to the wellhead in five days. Although on the fifth day,

But there was no time to leave the wellhead. On the fifth night, I had to fall two meters, and on the sixth day, I had to climb for two-thirds of the day before I could actually climb out of the wellhead."

The students around him became obviously quiet and seemed to be thinking.

Li Xuan's words seemed to make sense. The classmate who asked the question suddenly realized and said: "Yes, it should be like this. He deserves to be number one in the province..."

Li Xuan: “…………”

He didn't realize the trap of this question at first. This question was not a test of mathematics, but a test of his eyesight. Li Xuan usually rarely made mistakes when reviewing questions, and rarely failed to notice key information in the question.

Take another look at the question. The last question in this question is not about how many days it takes to climb out of the entrance, but how many days it takes to climb out of the bottom of the well. The question is actually not very rigorous. Li Xuan thought about the key points clearly and did not dwell on his own mistakes in reviewing the questions.

Obviously the title was not clearly stated.

He was too stubborn to admit his mistakes.

Finally, he glanced at the title of the book, "A Collection of Mathematics Questions to Test Your IQ". Li Xuan, whose IQ was insulted, was speechless for a moment.

But then again.

For this question, if the depth of the wellhead is unknown x and the time to climb out is y, according to this question, there should be an equation about y and x. Using xy to establish a coordinate system, the function of y with respect to x should be shown as a jump

A collection of ascending line segments.

Li Xuan thought of this, picked up a piece of scratch paper, and silently listed the equations.

When other students saw Li Xuan making equations, they were stunned for a moment at first. Then they saw the unknowns next to the equations, and then they understood what Li Xuan was doing. Finally, they were all in a daze, astonished by Li Xuan's ability to think divergently.

"I'm going to the bunker..."

"That's right, if this were a national high school mathematics competition, we wouldn't ask such a simple question. Let's just calculate this kind of equation..."

"The Great God is the Great God!"

The classmates were talking a lot, and the way they looked at Li Xuan changed, as if they were looking at a monster.

After finishing the equations, Li Xuan put away his pen.

But at this time, Li Xuan suddenly thought, if the snail walks at the same speed during the day and night, but the snail climbs up during the day and falls at night, and the time between day and night is different, what is the equation?

At the vernal and autumnal equinoxes, the sun shines directly on the equator, so day and night are of the same length all over the world. At other times, the day and night are not the same length in the northern and southern hemispheres. This question becomes related to the length of day and night. If we still need to find the relationship between day and night, the problem is

It's getting harder.

Li Xuan frowned, wondering what the time of day and night had to do with each other?

Let’s make it simple first. Assume that the place is in Yangcheng and the time is today. From now on, the snail starts to crawl. How many days will it take to crawl out of the well?

Thinking about it this way, this question becomes a bit interesting.

Sunlight is parallel light. It shines on the spherical surface of the earth. The earth's axis has an inclination angle of 23.5°. The length of day and night can be obtained from the direct point of the sun.

From today's date, we can roughly calculate the location of the direct sun point. Yangcheng is around 22° north latitude. According to this method, we can quickly calculate the length of the day in Yangcheng at this moment.

What about around the world?

Obviously, there is a certain relationship between the date and the latitude of the direct sun point. If the latitude of the direct sun point is used as an unknown quantity instead of the date, and the latitude of the direct sun point is set as an unknown quantity, the problem will be simpler.

.

Li Xuan first drew a ball to represent the earth, first calculated the situation in Yangcheng, and then extended it to all locations in the world. He calculated the latitude of the location as an unknown quantity.

The idea is to use the day arc divided by the dusk line and the ratio of the line segments of the night arc to calculate the day and night time.

Seeing Li Xuan lowering his head to calculate, the calculation was filled with a large piece of draft paper, which vaguely wrote the walking speed of a snail, the relationship between day and night time and latitude, all the students were stunned:

"Is this a fairy?...I don't really understand the realm of gods."

"What, I'm really disturbing..."

"I can't understand what I'm doing, uh, I'll just run away..."
Chapter completed!