Substitute Teacher

Li Mo could tell at a glance that it wasn't human... uh, it wasn't homework.

Note that this is a mathematical substitution cipher.

Find the particular solution for each line of the differential equation, take the alphabetical number corresponding to the constant term, and then restore the order using the polar coordinate formula at the bottom to read the plaintext.

Li Mo focused on mental arithmetic and quickly translated the contents of the letter:

[Take this letter to Mansion No. 17 in Glenwell City, in the north. The doors of the Duchy Academy of Sciences are always open to true geniuses; do not be buried with a corrupt nation.]

--Holy crap!

Li Mo was greatly shocked.

What the hell, Mr. Harrison? He's a spy from the Duchy!

He expressionlessly folded the letter in half and stuffed it back into the envelope.

Going to the duchy is impossible, absolutely impossible in this lifetime. I've heard the people there like to eat children...

The question is, should we report Harrison or not?

Reporting him seems rather unethical, considering Mr. Harrison has been quite kind to me; but not reporting him risks getting myself into unnecessary trouble with this letter.

As I hesitated, Estelle arrived.

She doesn't seem to be in a good mood today.

Last night at the governor's private residence, she really just wanted to call Harrison over to give her a math tutoring session.

Who would have thought that Special Envoy's Office arrived at the hotel and revealed their identities and purpose, Mr. Harrison lied and said he had a stomachache and needed to use the restroom, then climbed out of the hotel's first-floor back window and ran away!

Although the Black-Robed Court Guards had already silently followed them, Estelle became increasingly depressed the more she thought about it when she woke up in the morning.

Why are you running away? Am I that stupid? You really don't want to tutor me in math?

Class time.

Mr. Hall, the homeroom teacher of Class One, walked in.

He clapped his hands and said, "I have something to inform everyone. Mr. Harrison had a sudden family emergency last night, and he has submitted his resignation to the college and left Mondel Town overnight."

The students reacted in various ways.

Last night, a group of people were arrested in town, and this morning, the math teacher resigned and ran away... It's hard not to connect these two events.

Estelle remained expressionless, continuing to gaze out the window while resting her chin on her hand.

Mr. Hall sighed and said, "The academic affairs office had originally arranged for Teacher White of Class 2, to substitute for the class today, but Teacher White had an acute attack of pharyngitis this morning and couldn't speak at all. The math teachers from other grades also have classes scheduled for this period, so they really can't make it."

As he spoke,

Mr. Hall stepped down from the podium and went to Li Mo's desk, saying, "Li Mo, the entrance exam is coming up soon, and everyone's math review progress at this stage is crucial and cannot be delayed. So... could you please come up to the front of the class today and go over yesterday's comprehensive test with everyone?"

Li Mo: "Uh..."

Actually, I'm quite busy and don't really want to waste time giving lectures.

Mr. Hall looked expectant. "Just go over the last few challenging problems... Of course, if it's inconvenient for you, I'll let everyone study on their own."

Li Mo glanced at Estelle and suddenly felt that lecturing was also meaningful.

He then said, "Alright, then I'll tell you two stories."

Mr. Hall nodded. "Great, then the podium is yours. I'll listen from the back."

Li Mo walked onto the podium.

--The masterclass is here.

He didn't do the comprehensive test paper at all yesterday.

Of course, he didn't need to prepare this kind of test paper in advance.

He borrowed the exam paper from a classmate, glanced at it, and immediately knew how to explain it.

"Please open your papers. I will try to explain slowly. If you have any questions, please raise your hand."

"This problem asks for the maximum value of the surface area intercepted by the focal chord of the parabola."

"I don't know how you guys did it before. It seems like you just substituted the equation of the line and calculated it by hand? Did you end up with a fourth-degree polynomial? It's easy to make mistakes when calculating that."

Many students in the audience nodded in agreement; fewer than three students in the class got this question right yesterday.

"Today I'll teach you a lazy method: directly take the first derivative of the tangent slope, set the derivative to zero, and you can pinpoint the coordinates of the extreme point in three steps. Look at the blackboard: First, let the x-coordinate of the tangent point be a..."

Li Mo has already tried to slow down his lecture pace.

But his slow pace still required others to exert all their strength to keep up.

A girl in the front row, whose math skills were usually average, nudged Perry next to her and asked, "Perry, is the third line followed by 2a or 4a?"

Perry, without looking up, quickly jotted down notes. "The square of 2a, Li Mo just said, the coefficients are directly canceled out."

Did you understand?

"Don't talk to me yet. I'll try my best to listen, and I'll teach you after class if I understand."

"Okay, okay, you're busy, you're busy."

In the classroom, by the window, in the spot overlooking the king's hometown, Matthew remained completely silent throughout.

He came to school as usual today, which once again proves his strong mental fortitude.

After experiencing family misfortunes, Matthew was burdened with worries and learned to remain silent.

Interpersonal relationships can change in an instant.

He used to be jokingly called "Damn Guy" by everyone.

But there are always a few lackeys who follow him around like a servant.

But today... my little followers turned and ran away as soon as they saw me. What's wrong? Do they not like me today?

Matthew looked at Li Mo, who was speaking eloquently on the podium, and suddenly asked himself a question:

Why do we have to compare ourselves to Li Mo in everything?

Li Mo is not human.

I still don't understand what's so special about that so-called 1729.

He even suspected that Wayne had deliberately used it to annoy him...

Why bother arguing with someone like that?

I'm just an ordinary person; all I need to do in the future is to be better than I was in the past.

Matthew's good mindset lies in this: knowing he can't win, he chooses to make peace with himself...

After all, those who are happy give way, and those who want to have fun do so.

There was no deep-seated hatred between him and Li Mo. In the past, he was simply jealous that Helen always dated Li Mo. Now that he liked Estelle more, his old obsession seemed a little ridiculous.

Matthew rested his cheek on his hand, gazing at the clear sky outside the window.

In fact, he had only one wish since he was very young.

He longed to stand out, to be in the spotlight, to be the center of attention, and to make everyone in Mondel Town remember his name, Matthew Oliver.

I wish I had a chance to showcase my talents. Sigh.

The 45-minute lesson ended.

Mr. Hall in the back row was the first to stand up and applaud.

The students in the audience also joined in the applause.

Several students, holding the steps they hadn't fully understood, cautiously asked Li Mo for help.

Li Mo patiently answered the questions, then returned to his seat to begin preparing the content for the third academic salon.

In this episode, I don't plan to talk about pure mathematics.

The next goal is to light up Mondel Town.

So he plans to give everyone a science lesson about "electricity".

By introducing Ohm's Law, Joule's Law, and the basic principles of incandescent light, the project lays the groundwork for illuminating the town later.

Estelle appeared beside him at some point and asked softly, "What are you writing? A new math problem?"

Li Mo glanced at her and said, "This is the outline for the third salon's lectures. This time, I'm going to talk about something interesting."

Estelle's eyes flickered slightly. "Still in the afternoon?"

"Um."

Estelle paused for two seconds before saying, "Mr. Harrison is gone."

"Um."

"I've fallen behind in a lot of math class, and I was planning to get him to tutor me these next few days. Are you free after your salon this afternoon? I'd like to find a quiet place so you can tutor me."

Li Mo thought for a moment, "Sure, but the salon will end around 5:30, and the classrooms at the academy will be locked by then. Going to a coffee shop would be too crowded... How about coming to my place?"

"Sure, you have a study at home, it should be quieter than outside, and you won't be disturbed."

Xiao Xi finished speaking.

Helen quietly raised her hand and said, "Li Mo, I also want to go to tutoring..."

Li Mo: "Come on, all of you."

Anna blinked and said, "Then I'll cook dinner for the three of you tonight."

After hearing this, Li Mo suddenly had an idea.

The hand-made generator I made a few days ago is still sitting at home. The workshop might be able to send over the first batch of carbonized cotton fibers and vacuum-sealed glass bulbs today.

After the afternoon salon covered the theory, in the evening, Xiao Xi, Helen, and Anna happened to be home to help out.

How about... after finishing my math class tonight, I try making an incandescent light bulb?