Chen Zhuo placed the test paper flat in front of Coach Xu.
"Coach, I’ve finished today’s test."
Chen Zhuo’s voice wasn’t loud, sounding steady in the quiet seminar room.
"I’m going to the library to look up some materials."
Coach Xu was taken aback.
He glanced down at his watch.
A little over an hour had passed.
Coach Xu’s gaze fell on Chen Zhuo’s test paper.
He saw the rows of matrices and determinants in the answer section for the final problem.
The corner of Coach Xu’s eye twitched.
He picked up the stainless steel thermos by his side, unscrewed the lid, blew on the floating tea leaves, and took a sip.
"Go on. Be back to assemble at two-thirty."
Chen Zhuo nodded and walked out of the seminar room.
The door closed softly.
Dead silence returned to the room.
Zhang Bai stared at Chen Zhuo’s empty seat, his fingers tightening around his pencil. He looked back down at his own scratch paper, which was covered in auxiliary lines.
Suddenly, the lines felt chaotic.
He walked out of the administration building.
A wave of heat immediately enveloped him.
Chen Zhuo followed the tree-lined path deeper into the campus.
The Provincial Experimental School campus was vast and well-landscaped.
Since it was summer vacation, the paths were nearly deserted.
Following the directions Lin Yi had given him, Chen Zhuo arrived in front of a building with a red-brick exterior.
The library.
He pushed open the heavy glass doors, and a blast of cold air from the central AC rushed toward him.
The first floor was an ordinary reading room, its wooden shelves lined with various magazines and newspapers.
Chen Zhuo greeted the librarian—whom he’d met with Lin Yi a couple of days prior—and went straight up the stairs to the third floor.
The third floor was spacious and empty.
In the far back was a relatively secluded area.
A few rows of tall, metal bookshelves were covered in a thin layer of dust.
The lighting here was dim.
Chen Zhuo walked over to a bookshelf.
His gaze swept across the rows of thick book spines.
The covers were mostly dark blue or deep red—no flashy designs, just gold-foil lettering.
His finger stopped on a thick spine.
He pulled it out.
Two simple English words were printed on the cover.
Abstract Algebra.
Carrying the book, Chen Zhuo walked to a corner by the window.
There sat a row of old, connected vinyl sofas.
Sunlight filtered through the leaves outside, casting dappled shadows across the sofa.
Chen Zhuo sat down and flipped open the book’s table of contents.
He leaned back on the sofa, one leg crossed over the other’s knee.
As he occasionally turned a page, his fingertips would pick up a bit of dust from the old book, which he would nonchalantly wipe on his pants.
He didn’t read fast.
Even for someone like him, this kind of high-level pure mathematical theory had to be digested slowly.
Back in Zeyang, he could never find original textbooks of this caliber.
The bookstores there only sold study aids, and the city library only had old translations from the 1980s.
Now, he was like a dry sponge tossed into a basin of water.
He needed this underlying logical framework.
He knew what he was going to do.
Aside from returning to the seminar room for the afternoon meeting,
for the entire afternoon,
Chen Zhuo sat in that corner.
Occasionally turning a page.
He was so quiet, it was as if he had merged with the old metal bookshelves.
「The next day.」
The air conditioning in the seminar room was once again on full blast.
The test papers were handed out.
Today’s problems were harder than yesterday’s, requiring even more calculation.
Zhang Bai was in surprisingly good form today.
He encountered a geometry problem with a model similar to one he’d once seen in some internal-use materials.
He excitedly started drawing on his scratch paper.
He pinpointed the auxiliary line perfectly.
Following that line, the entire complex geometric solid was ingeniously dissected.
Using pure Euclidean geometric theorems, he constructed a rigorous, step-by-step proof.
After writing the final word, Zhang Bai let out a long sigh of relief.
He glanced at his watch. Two hours and ten minutes.
It was a time he could be proud of.
He stood, picked up his test, and walked over to Coach Xu.
As he turned in his test, his eyes were inevitably drawn to a paper already on the coach’s desk.
It was Chen Zhuo’s.
He had left the seminar room half an hour ago.
Zhang Bai’s gaze paused for two seconds on the final problem of the test.
No auxiliary lines.
No elegant geometric dissections.
Only a coordinate system and cold, unforgiving rows of matrix transformations.
All the geometric variables had been brutally converted into numbers.
With sheer computational power, Chen Zhuo had turned a geometry problem that required immense talent and intuition to crack into a mere step-by-step arithmetic exercise.
Zhang Bai stared at the neat equations.
A sense of powerlessness washed over him.
His own elegant, artistic proof, the one he was so proud of, seemed both convoluted and fragile in the face of Chen Zhuo’s unreasonable, industrial-grade brute force.
It was a crushing blow from a higher dimension.
Zhang Bai silently placed his test underneath Chen Zhuo’s.
He turned and walked back to his seat.
He didn’t pull out his notes to review.
Instead, he took out a blank sheet of scratch paper and tried to recall the steps for matrix rank reduction he had just seen on Chen Zhuo’s paper.
During the break.
Coach Xu stepped out with his thermos.
Only a few students remained in the seminar room.
Zhang Bai, holding his scratch paper, stood up. After a moment’s hesitation, he walked over to Chen Zhuo’s seat.
Chen Zhuo was leaning back in his chair, resting with his eyes closed, idly fiddling with an eraser in one hand.
"Um..."
Zhang Bai’s voice was a bit hoarse.
Chen Zhuo stopped fiddling with the eraser and looked up.
Zhang Bai placed the scratch paper in front of Chen Zhuo.
On it, he had written out half of a matrix equation from memory.
"On your test just now, step three, with the rank reduction of the determinant to find the normal vector... how did you determine the positive and negative signs at a glance?"
Zhang Bai spoke in a hushed, deferential tone.
"When I use the traditional method to calculate this plane, I have to find at least two perpendicular auxiliary lines. With your method, I get stuck at the expansion step."
Zhou Kai and Lin Yi looked over.
Nearby, Li Nanbai and Mo Xiaoyu also stopped what they were doing and listened quietly.
Chen Zhuo glanced at Zhang Bai’s tense shoulders and chuckled softly.
"Don’t stand." He hooked a nearby empty chair with his foot. "Sit and talk."
Zhang Bai hesitated for a second, then pulled the chair over and sat.
Chen Zhuo picked up a mechanical pencil and slid Zhang Bai’s scratch paper into the space between them.
The pencil tip touched the paper.
"Here."
Chen Zhuo drew a line under the second row of the determinant.
"When you expand along the first row, the signs alternate. Look at the algebraic cofactor of this element."
He quickly jotted down two second-order determinants beside it.
"You don’t need to memorize it by rote. When you’re establishing the coordinate system, pick the vertex with the most edges as the origin. That guarantees that a large number of your coordinates will be zero."
Chen Zhuo sketched a simple diagram on the scratch paper and gently tapped the desk with his pencil.
"The more zeroes you have, the more of this cancels out during reduction. You can do the rest in your head."
Zhang Bai stared at the simple numbers.
It was as if the final paper-thin barrier in his mind had been pierced.
The computational hurdle that had stumped him for more than ten minutes just... dissolved.
"Geometric constructions are definitely elegant."
Chen Zhuo put down his pencil and leaned back, his tone casual.
"But time in an exam is a finite resource. If you can’t find the game-changing auxiliary line within ten minutes, stop looking for it."
He tapped the coordinate system on the paper with his finger.
"Just build the coordinate system and brute-force it. The person grading the test doesn’t care how elegant your method is, only whether the final answer is correct. Once you master this tool, you can save twenty minutes on the big problems."
Zhang Bai stood there.
He looked at the equations on the scratch paper.
He nodded, then put the paper away.
"Thanks."
"No problem."

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