I was a top student in America.

With that in mind, Li Ao picked up the pencil Brown pushed towards him and began to solve the problem.

The problem asks for the maximum and minimum values ​​of a quadratic function: Given that x and y are both positive numbers and x + y = 4, find the maximum value of xy.

The idea was already there; for him, this wasn't even a warm-up.

Without pausing for a moment, he immediately wrote down the first solution on the paper.

Replace y with (4-x), substitute it into the original expression, and transform xy into a quadratic function of x. Then, complete the square to obtain the vertex form and directly read the maximum value.

The process is simple and clear; the answer can be obtained in just three or four lines.

But Li Ao did not stop writing. Right next to the problem, he wrote down solution two.

He wrote a short equation on the paper.

The arithmetic mean inequality states that the arithmetic mean is greater than or equal to the geometric mean.

By substituting the conditions, the conclusion can be obtained directly with just one line of equation.

After finishing the first question, he casually flipped to the next two questions that Brown had pointed out.

Although the difficulty of the questions varies greatly, they are, after all, exercises from the textbook, and all the content is just a variation of the example questions.

With the ability to apply knowledge to new situations, he could immediately recall similar examples at a glance and find the precise entry point to proceed step by step.

The noise in the corridor gradually faded away, and the numbers on the draft paper filled his vision. He was so engrossed in solving the problem that he completely forgot about the math teacher standing next to him.

Meanwhile, by the back door of the classroom, DeMarcus lingered, one hand hooking his backpack strap, not leaving.

At Wyndham High School, students can do whatever they want without anyone interfering, and no teacher is willing to stay behind to give students a private talk.

Brown's decision to have Li Ao confront him alone after school today is definitely not a good thing.

He leaned against the door frame without moving, inwardly worried for Li Ao.

Outside in the corridor, there were one or two delinquent students who weren't in a hurry to catch the school bus. They deliberately lingered at the door, peeking out and waiting to see what would happen.

"Cheating on a stupid test? That's fucking insane."

Lin Jinni in the front row was also delaying.

She pretended to pack her schoolbag, pulling the zipper back and forth several times without closing it, glancing at the podium every now and then out of the corner of her eye.

At this moment, Brown was standing next to Li Ao.

At first, he crossed his arms, completely adopting a "let's see how you expose yourself" attitude.

When Li Ao wrote out the first solution using the completing the square method, Brown's expression remained relatively unchanged.

The approach was clear, the solution was correct, and it could even be considered a clever and elegant solution.

But this is still within the scope of the textbook, and if we have to explain it, we can barely say that we memorized the question by rote.

But when he saw Li Ao immediately write down the mean inequality on the paper, he suddenly lowered his arms, which were clasped in front of his chest.

The old man frowned.

He certainly recognized this method, but it was definitely not something that could be found in the high school Algebra II textbook.

This is the content of the AP Math course (Advanced Placement).

How did a student who usually just sleeps in class learn the mean-mean inequality?

Brown didn't say anything, but involuntarily took half a step forward.

Watching Li Ao continue working on the next few questions, he couldn't stand it any longer, so he simply pulled out an empty chair in the first row and sat down to watch.

What started as a condescending scan turned into a line-by-line reading of Li Ao's deduction process.

The more he looked, the more turbulent his heart became.

Li Ao not only had a clear mind, but each step of his transformation and substitution was also highly purposeful.

No student who can only memorize by rote can write out such a process. Only by truly understanding the underlying logic behind these mathematical structures and integrating it into their knowledge can one be so adept at it.

Just as Brown was engrossed in reading, Li Ao finished writing the answer to the last and most challenging question.

He casually tossed the pencil onto the table, relaxed his shoulders, and let out a long sigh of relief.

As soon as I looked up, I was met with a big face next to me.

Li Ao was startled and leaned back half an inch: "Mr. Brown?"

He was so engrossed in doing his homework that he didn't even notice when the old man sat down next to him.

Brown ignored his astonishment and simply reached out and snatched the sheet of draft paper covered with equations.

His rough fingers pointed to the second solution to the first problem, and his voice was a little deep: "Who taught you this method? This isn't something from the textbook."

Li Ao glanced at the arithmetic mean-geometric mean inequality he had written and casually replied, "I learned it myself by borrowing books from the public library."

Brown didn't respond.

He had spent nearly twenty years in that awful place, Wyndham High School, and had seen too many students left to fend for themselves.

A poor student who spends all his time in the library studying math on his own?

No one would believe it if I told them.

But that draft paper was now clutched in his hand.

Brown took a deep breath, stood up from his seat, and walked back to the podium.

He picked up the test paper that had been turned face down on the table, with a bright red "98" drawn on it, walked back to Li Ao's desk, and slammed the test paper onto the table.

There was no explanation.

But in this shabby school where anyone caught cheating is immediately expelled, the act of returning the exam paper is itself tantamount to acknowledging the grade.

Just as Li Ao was about to pack his bag and leave, Brown suddenly remembered something and called him back:

"Wait a minute, didn't you ask me about competition preparation materials a few days ago... Are you really planning to take the AMC exam?"

"Yes," Li Ao answered readily.

Brown sighed and stared at him for a second.

He seemed to want to say something more, such as the exorbitant registration fee or the lack of relevant guidance resources at Wyndham High School, but he swallowed those discouraging realities back before he could finish speaking.

Finally, the old man simply nodded: "Alright, good luck, go back now."

At the back door, DeMarcus was completely stunned as he watched Brown hand the test paper back to Li Ao.

He was too far away to hear what the two were saying, but according to the rules of Wyndham High School, shouldn't Li Ao be scolded and then taken to the dean's office?

Is this over?

Finished?

Lin Jinni, sitting in the front row, clearly caught the three letters "AMC".

The zipper on her backpack finally came zipped up with a "zip" sound.

Aside from Li Ao, perhaps only she and old man Brown in the whole class knew the true value of those three letters.

She watched Li Ao sling his schoolbag over his shoulder, and something else appeared in her eyes.

The group of troublemakers who had been waiting to see the spectacle were bored when they saw that Old Brown not only didn't lose his temper but also let the person go with a friendly smile. They muttered "FXXK" under their breath and left dejectedly.

There's absolutely no need to broadcast this over a loudspeaker.

In a rundown place like Wyndham where there are no secrets, the best endorsement is if the thugs in the hallways keep quiet.

Li Ao folded the test paper in half, stuffed it into his schoolbag, slung it over one shoulder, and walked out of the classroom.

As soon as he stepped out the door, DeMarcus rushed up from the back door and grabbed his arm.

"Dude! What's wrong with you?" DeMarcus's eyes widened, his face showing utter disbelief. "Don't tell me that old man Brown actually understood those cryptic symbols you drew in class these past few days?"

"More or less." Li Ao pulled his arm back and smiled.

Pushing open the door of the teaching building, the cold wind outside, mixed with the distinctive diesel smell of the South Campus, rushed towards me.

Li Ao tightened the collar of his coat and offered no further explanation.

But he knew very well that from the moment Brown returned the test paper to him today, his days of being invisible at Wyndham High School were completely over.

……