The atmosphere in the classroom is particularly harmonious in white tones.

In addition to Old Man Liu's subdued and frustrated speech, it is the sound of the pen tips of the students, which sounds like a symphonic concerto.

As a senior in high school, these students basically will not raise their heads as soon as they enter the learning state.

So naturally, no one noticed Su Mufeng's movements on the podium.

"The domain of the known derivative is (0,+∞)......" Su Mufeng muttered to himself softly, silently reciting the question, and began to write his preliminary answer on the blackboard.

As soon as the chalk fell on the blackboard, Su Mufeng was stunned.

The talent around him was stirred up almost instantly, churning and circulating, and merging into Su Mufeng's mind.

Su Mufeng suddenly felt that his eyes were clear, his brain seemed to be running countless times faster, and on the blackboard in front of him, the numbers and derivatives written in chalk also seemed to come alive and became extremely vivid.

His eyes widened in astonishment and he gasped.

"Does talent still have this effect?"

Su Mufeng's eyes were like torches, and he almost couldn't help laughing.

Originally, his talent for learning was only average, and the final exam of the second year of high school barely broke out, so he mixed into the real yàn class, and he has always been quite difficult to study.

Especially in mathematics, the requirements for talent in this subject are indeed too high, and students with 150 points of test papers who do not meet the talent standards cannot reach the point of more than 135 points even if they brush hundreds of sets of test papers.

In mathematics, Su Mufeng can only rely on the tactics of the sea of questions to repeatedly hone the regular question types in order to barely cope with the exam.

The "simulated conventional questions" on the blackboard in front of him, although Su Mufeng can usually answer them, they also need to be carefully considered, and even accidentally write a number wrong, that is, zero points.

"I thought I could only give up my studies and barely go to an ordinary school at most, but now it seems that even a top school like NTU has hope to compete!"

For some reason, thinking of Nanda, a girl with black-rimmed glasses appeared in Su Mufeng's mind.

"Are you going to be your junior? Sounds really interesting. ”

Of course, the first problem now is to solve this problem.

Su Mufeng eliminated distracting thoughts and began to calculate on the blackboard with full concentration.

The sound of chalk and blackboard colliding began to sound rhythmically.

Under the staggered flow of talents, Su Mufeng's spirit was unprecedentedly concentrated, and all thoughts and distractions that had nothing to do with mathematical theories were completely abandoned.

Gradually, he even forgot why he was doing this question, and forgot that he was standing on the podium.

In front of Su Mufeng's eyes, there was nothing but gray-white numbers and formulas.

Therefore, he did not realize that the difficulty of this question was actually countless times more difficult than the originally conceived "mock conventional questions".

The number calculus is too cumbersome? Can't write on the blackboard?

Multiplication and division of less than five digits, mental arithmetic solution.

Solving higher-order multivariate equations? Haven't learned the formula?

Finding the root formula is derived by itself, and it is really not possible to forcibly substitute it for verification.

Need advanced math?

With a little impression of the teacher's talk about the relevant question types, I completed it by myself, and the missing parts were completed through the guò high school course.

Gradually, Su Mufeng was about to fill most of the blackboard in this state of selfless devotion.

Under the podium, almost all the students in a class were immersed in the sea of questions, and none of them raised their heads to look at the blackboard.

Old man Liu's lecture continued.

“…… The third solution to this problem is basically like this, and the students will calculate the results by themselves after class, and I will continue to explain the fourth solution——"

Finally, a boy couldn't stand the endless "Xth solution", sighed and put down his pen, ready to rest for a few seconds.

"Old man Liu is really enough, the answer to a question can be written on three pages, which is almost comparable to the kind of perverted question he copied on the blackboard."

While complaining in fragments, the boy casually raised his head and glanced at the blackboard very casually, wanting to see if the unlucky guy had written two or three lines before he was punished.

In the process, he even yawned lightly.

The next moment.

His eyes glazed over.

The originally relaxed and natural expression completely froze on his face, he grew his mouth and kept yawning, but his mouth grew bigger and bigger, and finally he could stuff two duck eggs.

"I, I, I—"

He shivered, his fingers trembling and grasping the cuffs of his tablemate, shaking constantly.

The tablemate was still taking notes, flicking his sleeves impatiently, and said without raising his head: "What am I, am I, the sheep is crazy?" ”

"I--"

The same table was stunned, looked up at the expression of the thing next to him, almost like the Tiangong-1 astronaut who saw a comet hit the earth, and looked at the blackboard with his line of sight in wonder.

The next moment.

His expression became equally exciting.

……

On the podium, Old Man Liu was still frustrated.

"There is a certain difference between the fourth solution and the third solution...... Ay? What are you all looking at? ”

Holding on to his old-fashioned glasses, Old Man Liu looked at the group of students in the corner of the classroom in puzzlement.

They were all looking up, like performance artists, with their mouths wide open and staring blankly at the blackboard.

Old man Liu waved the exercise book in his hand with some dissatisfaction, and shouted, "What are you looking at!" I'm still talking about it! Is there an answer on the blackboard? ”

With his scolding, some of the students who were immersed in the questions also raised their heads curiously and looked at the blackboard.

Then, the expressions of the group of "performance artists" spread wildly in the classroom like a virus.

In the end, except for Old Man Liu, everyone looked at the blackboard with a blank face.

Old man Liu was also stunned, he held his glasses again, a little confused, and said, "What are you looking at?" Is there really an answer on the blackboard? ”

"Old, teacher......"

The math class representative looked confused, and his voice trembled: "Really, there is really an answer-"

Old man Liu frowned and scolded, "What are you kidding? ”

The representative of the math class couldn't help but laugh: "Teacher, turn around and take a look." ”

Old man Liu shook his head, thinking that today's students are really difficult to understand compared to a few decades ago, and then turned around, holding on to his old-fashioned glasses, and squinted at the blackboard.

"Smack-"

The vintage glasses fell to the floor, and the lenses shattered.

Old man Liu's expression was surprisingly consistent with the countless students under the podium.

His eyes were glazed and his expression stiffened.

The blackboard, which occupies most of the walls, is covered with gray-white chalk letters, dense but well-organized.

The logical system of known, because, so, and proven is arranged in an orderly manner, with complex numbers up to five digits nested in long and unfamiliar formulas, and in Cartesian coordinate systems, towards a thousand strange function images staggered and overlapped.

Lopida's law, Lagrangian median theorem, Taylor's formula...... Countless higher mathematical laws are applied in this long process of proofing.

On the other side of the blackboard, a young man was still standing straight, holding an unknown number of pieces of chalk, continuing to write.

At his feet, chalk ash had fallen to the ground, and the floor of the pulpit was full of his footprints in the dust.

The world seemed to freeze at this moment.

In the huge classroom, there was no sound other than the sound of chalk and blackboards colliding.

All the students, as well as Old Man Liu, held their breath, staring at the blackboard covered in handwriting, and the back of the tall young man.

The mathematicians sitting in the first row put down the pen in their hands, pushed their glasses, and looked at the handwriting on the blackboard with solemn eyes, as if they were thinking about something, but in the end they could only shake their heads and sigh.

More of the students recovered from the shock and froze for a moment, then picked up their pens and began to record the young man's handwriting.

Old man Liu leaned down, picked up the half-broken glasses, put them on the bridge of his nose, and laboriously looked at the proof formulas with the remaining lenses.

The corners of the old man's mouth gradually hooked up a smile.

He sighed, but there was no disappointment in his sigh, but full of relief.

Finally, the long writing ended.

"To sum up, the problem is proven."

Repeating the last line softly, everyone saw that the young man closed his eyes.

He turned around and gently placed the chalk on the podium table.

The next moment.

I don't know who started clapping, and then the applause spread and echoed through the classroom.

Old man Liu stepped forward, looked at Su Mufeng, who was staring blankly, and patted him on the shoulder.

"That's the IMO topic last year."

"You're doing a good job...... No, it's great! ”