Chapter 109：

But by the sophomore year, things are different.

The difficulty of high numbers has risen a step in vain.

This increase in difficulty is without warning.

At this time, it is not so easy to pass the exam. As for the high scores, you need to work as hard as you did in high school.

When you start to learn calculus, most people will be dumbfounded.

What is this special?

When you come into contact with linear algebra and complex functions, I am afraid you will doubt life.

Who am i?

Where am i?

What am i doing?

Lin Xian's reading speed is very fast, because many of the knowledge points in the book are learned in high school mathematics, so he just glanced at it. With the blessing of 100% memory, it will be quickly recalled.

Time passed by every minute and every second.

On the podium, Dai Pingbo was still explaining the knowledge in the textbook in a simple and profound way.

Wang Zejing was lethargic, Zhang Kai absently looked at the back of the girls in the front row...

Only Lin Xian read the book attentively.

Ling Youyu raised his head for the third time and glanced at Lin Xian secretly.

After discovering that he hadn't paid attention, he looked up carefully.

I have to say that men are the most attractive when they are serious about doing something.

Looking at his profile, Ling Youyu was addicted to it unknowingly.

At the very beginning, she saw Lin Xian flipping through the book quickly, thinking that he was opening it randomly.

But gradually, Ling Youyu found that something was wrong, because Lin Xian's expression was extremely focused. This concentration was not deliberately disguised, but inadvertently revealed.

He is really amazing!

Ling Youyu put his cheeks in his hands and couldn't help but sigh in his heart, but at the same time he was a little bit distressed.

What to do, I like him more and more

Will he like himself

I should like it... He gave his own bracelet today.

Thinking of the bracelet, Ling Youyu's mouth could not help but slightly lifted, revealing a sweet smile.

There are some questions at the back of the textbook. At this moment, Lin Xian has taken out his pen and is working hard to solve the questions.

The sixth edition of TJ is simpler than other editions.

It is simple because some knowledge points have been deleted in this edition, and the content is not as much as other editions.

Basically non-985 or 211 colleges and universities, most colleges and universities will use the sixth edition, unless they are majors in mathematics, they will choose the fifth or even the fourth edition.

Therefore, for him, the topics on the books are not at all difficult.

The pen in Lin Xian's hand was stopped until the last one with an asterisk question.

Let A be the mxn matrix and B be the nxm matrix and mn, and prove that det(AB)=0.

"Hey, this question is interesting."

Lin Xian pondered for a moment, his brain turned rapidly, and the various knowledge points he had learned before kept flashing in his mind.

After thinking about it for a while, Lin Xian suddenly heard the teacher say to dismiss the get out of class.

A large class is divided into two sections, each section is 45 minutes, and there will be a 15-minute break in between

Looking at Professor Dai Pingbo, Lin Xian's eyes lit up and he walked forward quickly holding the textbook.

"Mr. Dai, wait a minute."

Dai Pingbo was about to go out with a teacup, and stopped immediately when he heard a student calling him.

Looking at Lin Xian, Dai Pingbo smiled and said, "Classmates, do you have any questions? Teacher Dai, I have some doubts about this question. Let A be the mxn matrix, B be the nxm matrix, then AB is the mxm matrix. What should I do next? Proof?"

Lin Xian pointed at the question and asked.

Dai Pingbo gazed at the book and looked at the densely packed answers to the problems on it. He couldn't help being a little surprised.

The handwriting of these answers hasn't been done yet, obviously just not long after they were written.

Suddenly, Dai Pingbo became interested, took a close look at the problem, and couldn't help but smile: "It's normal that you can't solve it. This is a typical linear algebra problem. Because of mn, r(AB)sr(A)≤n

While talking, Dai Pingbo picked up a pen and wrote down a line of formulas.

"Understood!"

Looking at the answer in the book, Lin Xian suddenly realized, thanking him, "Thank you, Teacher Dai."

"No thanks!"

Dai Pingbo waved his hand and asked with interest: "Have you finished your freshman high maths by yourself?"

"Almost!" Lin Xian said calmly.

Wait!

Finished self-study of freshman high numbers?

The students in the classroom were suddenly full of black question marks.

Damn it, do you want to be so awesome?

And why don’t you go to Qingbei if you are so awesome? Why come to Jincai? Is the FD cafeteria not tasty, or the TJ dormitory beds are too hard? So angry!

"What's your name, classmate?" Dai Pingbo asked with a smile.

"Lin Xian!

Dai Pingbo asked, "Lin Xian, have you ever thought of changing your major? I think applied mathematics is very suitable for you!"