After taking the advice, I became a top student.

"Teacher Hu, Chen Mo just wanted to study and didn't disturb anyone else."

Before Chen Mo could answer, Shen Qingyi spoke first.

Hu Xin looked at Shen Qingyi with some surprise, but the words of a good student like Shen Qingyi were quite credible.

The other students in the class also looked at Shen Qingyi in surprise, becoming even more certain of their guess.

Shen Qingyi knew she was in trouble the moment she said those words, but she didn't regret them too much.

Chen Mo sat next to her. After a class, she could tell that Chen Mo just wanted to study hard and didn't have any other thoughts.

As the class's academic representative, she felt it was her responsibility to help classmates like this.

Chen Mo was also somewhat surprised, not expecting Shen Qingyi to speak up for him.

However, he had already prepared his explanation: "Teacher Hu, I am quite nearsighted and can't see the blackboard clearly when I sit in the back row, so I would like to listen to the lecture in the front row. Don't worry, I will move back as soon as get out of class is over and it won't affect the other students."

Hu Xin was surprised again.

He had seen Chen Mo's math scores from the entrance exam two days prior.

72.

In his view, this score was already close to the cutoff line. If it were any lower, it would be very difficult to improve. However, if the student himself was willing to try to salvage the situation, it wouldn't be impossible.

As Chen Mo said, sitting in the aisle during class wouldn't affect his classmates, but it would be a bit of an obstacle for him. After all, he liked to wander around the classroom during class, and the lack of an aisle made it feel a little strange.

However, he was able to overcome this difficulty in order to fulfill his students' desire to learn.

He glanced at Shen Qingyi again, still unsure whether the little one was telling the truth.

He wasn't in a hurry; he figured he'd find out in the next class anyway.

"We've already covered functions in eight lessons, which is quite comprehensive. I believe everyone now has a deep and thorough understanding of functions."

Hu Xin stood on the podium, his gaze sweeping across the classroom like a king surveying his territory.

The students in Class 18 who are familiar with Lao Hu's style know that today's topic will definitely be an important one.

"Today, we'll talk about a challenging problem you'll almost certainly encounter during your exams: abstract functions and constructors..."

Seeing this, some students were disappointed. They had thought the teacher was going to teach Chen Mo a lesson for his misbehavior, but they didn't expect the teacher to just let it go so easily.

In their view, changing seats without permission is a very outrageous act, but it seems that the teacher doesn't see anything wrong with it.

Of course, some students were secretly happy.

With Chen Mo blocking the aisle, the teachers can't come down from the podium, so they can play on their phones during class with more peace of mind.

They hadn't expected such a pleasant surprise; they should have known better than to yell at Chen Mo so loudly before.

While attending class, Hu Xin kept an eye on Chen Mo in the aisle.

He nodded to himself, at least the little guy was paying attention in class and his attitude was fine.

It must be said that although Rongcheng No.1 High School is not a top-tier high school and cannot be compared with No.4, No.7, and No.9, Hu Xin is an excellent math teacher. As Chen Mo listened to Hu Xin's in-depth yet easy-to-understand explanations, many of his questions were easily answered. He discovered that learning was actually quite interesting.

He used to sit in the back row and would lose focus after a few minutes of class, feeling like he couldn't understand what the teacher was saying. But today, he found that he could actually keep up with the teacher's pace.

He was like a dry sponge, thirstily absorbing nourishment from the ocean of knowledge.

"Many students will definitely ask, 'Constructor functions are so complicated, what's the use of learning them?'"

After teaching for most of the class, Hu Xin felt that he had explained the constructor function very clearly. Now, it was time to put it to the test.

"Okay, let's look at a question next."

As he spoke, he clicked the mouse, and a brand new question appeared on the projector.

Figure:

"Everyone, take a look at the question, think about it first, and then read on."

Hu Xin knew that his classmates were eager to flip down to see the answers, but looking at the answers without thinking would result in poor learning outcomes.

Hu Xin glanced at the time and continued, "Okay, I'll give you five minutes to try this problem. Remember the constructor techniques I just explained."

After he finished speaking, he stood on the podium and began to observe the students' reactions.

This question is quite difficult. He knows that many students will not be able to solve it in five minutes, but class time is limited, and he can't really give students ten or twenty minutes to think about it.

Many students have already started scribbling on their draft paper, while many others are still staring at the blackboard with a hint of confusion in their eyes.

Hu Xin knew that this was a normal phenomenon.

To his surprise, Chen Mo, who was sitting next to Shen Qingyi, was also writing and drawing.

"No, can he even understand the questions?"

He felt that the difficulty of this question was somewhat beyond the scope of the curriculum for a student who only scored 72 points in math.

He stepped down from the podium, wanting to see what Chen Mo was writing.

He had only taken two steps when he stopped again.

He was a student once too, so he understands how much pressure it can be to have a teacher watching you while you're doing problems.

Moreover, this is when tackling a difficult problem.

Based on his estimation of Chen Mo's strength, the other party was probably just scribbling on a draft paper right now. If he went over at this moment, the little guy would be embarrassed.

"Let's not discourage him!"

With a thought, Hu Xin changed direction and headed in another direction.

This question was indeed a bit difficult for Chen Mo, but the teacher had just explained the constructor function, and by following that approach, he quickly came up with a solution.

Since the problem asks for a comparison of the sizes of a=f(1), b=f(2)/4, and c=f(-3)/9, then we should just find a way to construct such a function.

Let's look at the given conditions again, as shown in the figure:

那幺两边同时除以一个x_1^2x_2^2，0除以任何数都是0，而左边就变成了[f(x1)/x_1^2-f(x2)/x_2^2](x1-x2)<0

现在就可以构造函数，令g(x)=f(x)/x^2，那幺原不等式就变成了(g(x1)-g(x2))(x1-x2)<0.

If the product of the two terms is less than zero, then one term is positive and the other is negative. So, regardless of whether the first term or the second term is greater than zero, we can easily conclude that the function with the larger independent variable has a smaller function value.

Therefore, the constructed g(x) is a monotonically decreasing function.

However, g(x) is not monotonically decreasing over the entire domain, but rather over (0, +infinity). But according to the problem, f(x) is an even function, and x^2 is also an even function, so g(x) is also an even function.

This was summarized by Chen Mo last night when he was reviewing the key points. There's a simple formula: for multiplying odd and even functions, even-even equals even, odd-odd equals even, and odd-even equals odd...

Returning to the problem, since g(x) is monotonically decreasing in (0, +∞) and is an even function, it is easy to obtain the graph of g(x).

Figure:

Returning to the question, a, b, and c are simply g(1), g(2), and g(-3). Based on the graph, the size relationship between the three can be seen at a glance.

Therefore, the answer should be D!

Chen Mo raised his head, feeling refreshed.

Shen Qingyi, who was standing nearby, also looked up, and clearly, she had also received the answer.

And now, less than half of the five minutes given by Teacher Hu have passed.

Shen Qingyi looked over at Chen Mo with some surprise, and was slightly astonished to see that he had the same answer as her.