He was outscored after scoring 520 points, but his status as a prodigy can't be hidden.

Lin Yu did not use triangular substitution at all.

He wrote the first line on the blackboard:

Let L(x, y, λ) = x² + y² - 2x - 4y + 5 + λ(x² + y² - 4)

The entire class fell silent.

Li Hao stopped twirling his pen, his brow furrowing. He stared at the λ symbol, frantically searching his mind for all the knowledge he had accumulated over three years of high school, but to no avail.

Lin Yu's wrist remained steady in the air as he continued writing.

second line:

∂L/∂x = 2x - 2 + 2λx = 0

∂L/∂y = 2y - 4 + 2λy = 0

∂L/∂λ = x² + y² - 4 = 0

The third row:

Solve to get x = 1/(1+λ), y = 2/(1+λ)

The fourth line:

Substituting the constraints, we get λ = -1±(√5)/2, corresponding to the extreme points (2√5/5, 4√5/5) and (-2√5/5, -4√5/5).

Fifth line:

f_max = 9 + 2√5, f_min = 9 - 2√5. Geometrically, f_max represents the extreme values ​​of the squares of the distances from a point outside the circle to two points on the circle.

After writing the last word, Lin Yu casually flicked his wrist.

The broken piece of chalk traced a parabola in the air and landed precisely in the chalk box three meters away.

He patted a bit of chalk dust off his fingertips, the whole process taking less than thirty seconds.

"Finished writing."

Lin Yu didn't even glance at Wang the Bald, put his hands in his school uniform pockets, and turned to walk towards his seat.

The classroom was so quiet you could hear a pin drop. Only the ceiling fan emitted a monotonous hum.

A few seconds later, Baldy Wang suddenly turned around and stared intently at the five lines of words on the blackboard. His eyes twitched, and his face turned pale and then red.

"Lin Yu! What are you scribbling about here?"

Baldy Wang slammed his hand on the lectern, spitting as he spoke, "Where in the high school syllabus did you learn to solve problems using these symbols? Where's the process? Where's the case-by-case analysis? You think you can get away with just making up a few incomprehensible letters and piecing together a result?"

The students below seemed to wake from a dream and burst into laughter.

"I knew it! How could he possibly solve this final problem?"

"Drawing a radical on the left and adding 'lambda' on the right—is this some kind of ancient summoning ritual?"

"This is hilarious! They even skipped the process and just forced the answer. They're treating Wang the Bald like an idiot."

Li Hao leaned back in his chair, making no attempt to hide his disdain: "Lin Yu, mathematics is a rigorous subject, not a stage for you to show off. You don't even know the most basic trigonometric substitution, yet you dare to concoct formulas here. If these five lines of writing can earn you points, I'll eat this table."

Su Qingwan gently shook her head. The stunning impression she had just made vanished completely.

All show and no substance. Faced with an insurmountable predicament, she resorts to such clumsy tactics to attract attention. Her choice was indeed correct; Lin Yu is destined to wallow in the mire of the lowest rungs of society, forever unable to reach the elite world she yearns for.

"Lin Yu, get out of the classroom right now! Stand in the hallway!"

Baldy Wang pointed outside the door and roared.

Lin Yu stopped in his tracks. He turned his head, looked at the furious Baldy Wang and the mocking Li Hao, and a faint smile appeared on his lips.

madness.

This is why he was reluctant to reveal his abilities before. Communicating with this group of people who only memorize standard answers is more exhausting than solving Goldbach's Conjecture.

He couldn't be bothered to explain. You can't discuss ice with a summer insect.

Just as Lin Yu was about to leave the classroom.

"He's using calculus to buy cabbage."

In the corner of the second-to-last row by the window, a clear, flat female voice suddenly pierced through the laughter of the entire class.

The laughter stopped abruptly as everyone turned to look at the source of the sound.

Xia Zijin was sitting in that spot.

She always wore an old school uniform that was a size too big, thick black-rimmed glasses that covered most of her face, and her bangs were almost poking her eyes.

In class, she was almost invisible, always alone and never participating in any social activities. Yet everyone held her in awe, because although she was always sleeping in class, she consistently ranked among the top three in the entire school.

Xia Zijing did not stand up. She held a pure black mechanical pencil in her hand, her gaze fixed on the five lines of words on the blackboard through her thick glasses.

"This is the Lagrange multiplier method."

Xia Zijin spoke calmly, simply stating an objective fact: "A method for finding the extrema of a multivariable function when its variables are constrained by one or more conditions. It belongs to the core content of university-level advanced mathematics, multivariable calculus."

The entire class fell silent.

Li Hao's face froze instantly; the words he had just uttered felt like a slap in the face.

"His derivation process is perfect. There isn't a single wasted word."

Xia Zijing's gaze shifted from the blackboard, across half the classroom, and landed on Lin Yu.

That was the first time Xia Zijing had ever looked a boy in the class seriously.

Her eyes, hidden behind black-rimmed glasses, gleamed with an almost fanatical thirst for knowledge, like an extremely sophisticated radar that had finally detected a signal on the same frequency.

"You've simplified the most challenging problem that would require high school students to fill an entire page of scratch paper into a solution that can be done in five lines. Lin Yu, you've saved yourself seven steps of basic derivation."

Xia Zijing's voice was soft, yet every word carried immense weight: "Your thinking speed is very fast."

Wang the Bald man's Adam's apple bobbed. He hurriedly flipped open the detailed explanation of the final college entrance examination question bank on the lectern.

On the last page of the answer explanation, in the extended reading section, there is a solution that is exactly the same—an example of a solution using the Lagrange multiplier method.

The results were completely identical. Even the values ​​under the square root were exactly the same.

Wang the Bald's hands began to tremble. He looked up at Lin Yu standing in the aisle as if he had seen a ghost. How could a poor student who only scored 105 on a placement test possibly master advanced calculus tools that even high school teachers rarely touch upon?

Li Hao's fingernails dug deeply into his palms. He stared intently at Lin Yu, his eyes filled with disbelief and intense jealousy. His pride and joy in solving problems beyond the curriculum was utterly crushed by Lin Yu's five lines of incredibly concise code.

Su Qingwan's lips parted slightly, her mind blank.

She looked at Lin Yu's clean and neat profile. He stood there, his school uniform open, accepting the gazes of the entire class that shifted from mockery to shock, yet his expression remained completely unchanged. It was as if what he had just written down wasn't an astonishing solution, but rather a crumpled piece of paper casually tossed into the trash can.

Is this really Lin Yu, the one who stayed up all night every day to copy her wrong answers?