Xueba, I beg you to go and escort him quickly!

"The value of m can be obtained by combining the equation of the straight line l as x=my+2 and the equation of the ellipse together with Veda's theorem..."

"Then……"

“所以就得到椭圆的方程为(x2/8)+（y2/4）=1……”

"It's over."

Yue Pingting looked at Xu Heng.

Xu Heng didn't interrupt Yue Pingting the whole time, and waited quietly for her to finish speaking.

"How? Nothing wrong, right?"

Xu Heng nodded, "It's not wrong, but...it's too complicated..."

"Come on, listen to me."

Yue Pingting pricked up her ears and leaned over to listen carefully.

Xu Heng, "From c/a=root 2/2, we can set a=2u, c=root 2u, b=root 2u, where u>0, put M(c, root c) into the ellipse Solved from the equation, u is the square root of 2, so the elliptic equation comes out, right?"

Yue Pingting digested for a while, then nodded with a smile.

Xu Heng also laughed, "You are much smarter than those students who participated in the Math Olympiad competition!"

Yue Pingting, "???"

Xu Heng, are you sure what you said is not ironic?

Xu Heng, "Let's look at the second question next."

"Assuming A(x1, y1) B(x2, y2) P(x0, y0), it is known that (x1, y1)=2(x0-x2, y0-y2), so..."

Yue Pingting pouted immediately, "Xu Heng! Isn't this the idea I just said? You, this?"

Xu Heng smiled, "That's right, that's it! So you could have made the second question, but you just passed it by."

Yue Pingting, "!!!"

Xu Heng continued, "The third formula is transformed into..."

"..."

"Analysis shows that the slope of the straight line l is not zero, so the equation of the straight line l can be set as x=my+2, which can be combined with the ellipse..."

"By Veda's theorem..."

"Finally, because the slope of the straight line is k=1/m, the slope of the straight line l is ±root 6/2."

After finishing the topic, Xu Heng gave Yue Pingting a summary, "The standard equation of the ellipse can be obtained by using the method of undetermined coefficients."

"To solve the problems related to the positional relationship between a straight line and an ellipse, the conventional idea is to first combine the linear equation and the elliptic equation, eliminate elements and simplify, and then use the relationship between roots and coefficients to establish equations to solve related problems."

"It is often simpler to solve problems involving chord length by using the chord length formula."

"The selection of the triangle area formula is also the key to solving the problem."

Yue Pingting nodded frequently, "Yeah! I'm digesting..."

This digestion does not matter...

Until the evening self-study and school.

As soon as school was over, Yue Pingting dragged Xu Heng to a corner where no one was around.

But by coincidence, Yue Pingting also touched something in Xu Heng's pocket that he shouldn't have touched.

.......

Chapter 221

When Xu Heng returned to the dormitory, he stepped back.

The things in his pockets... are gone!

In fact, it is really unnecessary, but Yue Pingting couldn't help being curious, "Is there any difference?"

So I tried it, and then...

Ah!

It seems that Yue Pingting was deceived by Xu Heng's lies again so logically.

Back in the dormitory, Xu Heng simply washed up and went to bed.

The dormmates haven’t seen Xu Heng for a long time, the miss is secondary, the main thing is to hear Xu Heng talk about Tsinghua and foreign affairs.

"Xu Heng, tell me!"

"Yes! Did Tsinghua gather many outstanding students from all over the country? What kind of super academics are they?"

"Is there anyone who can match you?"

Yang Kaixuan has been in the group, and some people have been talking about this and that in the group some time ago.

He knows everything.

Before Xu Heng could answer, Yang Kaixuan said, "Equally matched? Are you underestimating Xu Heng? Or do you really believe that there are classmates who are more talented than Xu Heng?"

Other roommates, "Uh... isn't there one? Isn't there one in the whole country?"

Yang Kaixuan, "Anyway, all I know is that when Xu Heng was in the intensive training class, he gave lectures to everyone in the evening self-study... It seems that he even said that those people were not as good as his classmates in the original third class."

Roommates, "!!!"

Xu Heng said the same thing as Yang Kaixuan, "Don't leave any pot unopened, go to sleep, everyone, ha... so sleepy!"

Yang Kaixuan put aside the topic, but——

Another topic then surfaced.

The roommates discussed in low voices, "You said Xu Heng hasn't come to class for so long, how will he do in the final exam?"

"The final exam will be fine-tuned this time, many people have been brushed away, and we don't know what the result will be!"

"You should still worry about yourselves, student Xu Heng doesn't need you to worry about it."

"That's right, he didn't study when he was in school, right?"

"exactly!"

"By the way, Yang Kaixuan, why don't you speak?"

"Yang Kaixuan? Why did you sleep? Didn't you always learn at 11 o'clock or even 12 o'clock?"

"Didn't you often say that you don't need to go to bed early when you are alive, and you will sleep forever after death?"

"what is it today?"

"Xu Heng also went to bed quite early."

"Damn! Xu Heng went to bed early because he was exhausted! Yang Kaixuan, what is this?"

Yang Kaixuan finally couldn't hold back anymore, the veins on his forehead were throbbing, "Because I don't want to participate in your topic..."

All the roommates, "???"

Once Yang Kaixuan started talking, he couldn't help but want to talk.

The roommates frowned and stared at Yang Kaixuan, "Is there something you are hiding from us? Tell me! What's the matter?"

Yang Kaixuan, "Don't talk, don't talk! Things that hurt self-esteem, go to sleep..."

"Don't! Don't go to sleep! Go to sleep after talking! If you don't talk, can you feel comfortable?"

"..."

The roommates were chattering, but Yang Kaixuan finally couldn't hold back.

"Okay! It's not as bad for a group of people as it is for one person..."

"Xu Heng came back this time and was called away by the principal. The principal told him that he didn't need to take the final exam because he was afraid that his grades would be too good and he would hit us."

very quiet!

In the ears of everyone, it is like a depth charge.

They never expected that the school would approach Xu Heng and tell him about this matter.

Suddenly, a classmate choked up, "Damn! You're so contemptuous!"

"Should I thank the school for taking care of us, or do I think the school did it on purpose?"

"Xu Heng is amazing, but... the school's approach is too inappropriate? The city doesn't care about it?"

Yang Kaixuan, "It looks like it means city."

All the roommates, "..."

Stop talking!

Say nothing!

Dormitory lights out.

"Hey--"

"Hey……"

"Hey... hey... hey..."

Resentful sighs came and went.

12 points.

Some roommates whispered, "Are you guys asleep?"

Within two seconds, someone replied, "No..."

12:[-].

Someone asked again, "Are you asleep?"

"Hey... I can't sleep at all, it's too uncomfortable... The school is too bullying!"

1 points in the early hours.

"Well... I can't sleep, who of you hasn't slept yet?"

"Hey……"

"Hey……"

"Hey……"

"Hey……"

There are six people in total!

Only Xu Heng fell asleep.

One person asked, and the remaining four sighed.

Wake up the next day.

Xu Heng got down from the bunk with a thud, which startled him.

These five people just woke up.

Xu Heng, "???"

"What's the matter with you, why are you up late?"

Everyone yawned, "Insomnia! Hey..."

Xu Heng quickly fell asleep last night.

Before Yang Kaixuan could tell a few people about Xu Heng not having to take the final exam, he fell asleep.

So Xu Heng didn't know.

Xu Heng looked left and right, looked at their exhausted faces, and sighed, "You guys, take your time and study, don't study so hard, you've been studying until midnight, right? Pay attention to your body!"

Everyone shook their heads, "No! We didn't study."