At first glance at this math problem, Xia Lu's head exploded.

Take a second look, emmm, it doesn't seem so scary.

This is called one raw and two ripe, no matter how difficult the topic, you will do it after a few more glances.

This math problem is actually a game.

Say a hunter and an invisible rabbit playing a game on an Euclidean plane.

Why do rabbits become invisible?

Is it an Ability Bunny?

Is it an Awakened Bunny?

Is it an aura rabbit?

Does it have invisible wings?

That's not the point, it's the question that follows.

Let the starting point of the rabbit A0 be the same as the starting point of the hunter B0, after the n-1 round, the rabbit is at the point An-1, and the hunter is at the point Bn-1, in the nth round of the game, the following three things happen in turn:

1. The rabbit moves stealthily to the point An, and satisfies that the distance between An-1 and An is exactly 1.

2. The tracking device reports a point Pn to the hunter, and the tracking device can only ensure that the distance between Pn and An does not exceed 1.

3. The hunter moves to the point Bn, and the distance between Bn-1 and Bn is exactly 1.

Q: Is it possible that no matter how the rabbit moves, and no matter what point the tracking device reports, the hunter can always choose how he moves, so that after a game of 10 to the 9th power, the distance between the hunter and the rabbit does not exceed 100?

Xia Lu's instinct was: no possibility.

Come, close your eyes, breathe deeply, feel again, feel with your heart.

This time, the instinct was still impossible.

Really, sometimes you have to trust your instincts.

Especially in the face of "Yes or No" type of proof questions, intuition often influences the direction of the respondent's judgment.

Xia Luti wrote three large characters in a critical style on the test paper: Impossible.

This wave is stable, and you can get at least 1 point out of 36.

The remaining 35 points depend on the proof process given by Xia Lu.

Note that it is important to note here that the teacher emphasized that the chase between the hunter and the rabbit takes place on the Euclidean plane.

Everyone is familiar with the difference between the Euclidean plane and the non-Euclidean plane, and the students who can enter the Hongyi Academy must know it well.

So, the key to this logic question is...... Xia Lu draws on scratch paper, and he tries to simulate a two-dimensional dotted and linear scene of hunters and rabbits chasing play on the Euclidean plane.

First of all, the first tracking device reports the point P1=A0, so no matter how the hunter moves, it is possible that the direction of the rabbit's movement is opposite, and the distance is A1B1=2.

So, due to the symmetry of the reporting point, the point Bs+n reached by the hunter after n steps may be below the straight line BsAs or above the BsAs.

Then, we get As+nBs+n≥BnCn≥√(d+√n^2-n)^2+1=......

So from d = 2 after the first step, after a maximum of 3332980 steps, the distance between the hunter and the rabbit is more than 100.

So after a 10 to the 9th power of the game, the distance between the hunter and the rabbit must be more than 100.

Therefore, the possibility of proposing the question cannot exist.

Certification.

I actually proved it!

Xia Lu slapped his thighs, cool.

Check the papers, no problem!

Look at the time, there are still 10 minutes to hand in the papers.

Look at Du Shengyong again, this little slut hit the street, he looked sad. Ask you to do push-ups, can you do push-ups and get a good score?

Qin Yibo, a big slut, is also very miserable, he has been biting the pen with a frown, biting the pen is useless, can you get 100 points if you bite the pen off? Tell you to play games, can playing games make you better? I have already sold my game skills!

The most pitiful thing is Zhang Kai, a super slut, he ...... , he handed in the papers, Zhang Kai handed in the papers in advance!

Zhang Kai, this guy, a slut with a perfect score in mathematics in the college entrance examination, is he so strong?

Xia Lu pinched the bridge of his nose to calm himself down.

What's wrong with me?

What the hell is wrong with me?

How can I treat my roommate like this?

Mentally abusing a roommate is also abuse, a mental atrocity.

Last night, I was so grumpy that I even wanted to beat up my roommate.

Anger, like lewdness, is a negative emotion.

Restraint, you must restrain the devil in your heart, Xia Lu.

Xia Lu waited until the last second to hand in the papers.

Xia Lu felt ashamed of his roommate, he went to KFC to buy a family bucket, and sent a message in the roommate group: "Go back to the dormitory at noon, I'll have a big meal." ”

Qin Yibo: "Eat, eat, eat, eat a ghost! I'm not in the mood, don't eat!"

Du Shengyong: "I failed the test, I was autistic, and I went on a hunger strike for three days to show my will." ”

Zhang Kai: "Look at the two of you, glass heart, Xia Lu come back quickly, I'll wait for you, mua~"

Xia Lu returned to the dormitory with the family bucket, and the three roommates were there.

Thanks to the wise leadership of the party, thanks to the prosperity and strength of the country, the life of the common people is becoming more and more prosperous, and college students have eaten KFC.

Xia Lu put the KFC family bucket on the table, the spicy chicken leg burger is round and full, the original flavor allows the chicken to be attractive in color, the egg tart exudes an extraordinary aroma, and even the cola is also added with ice.

Xia Lu said sincerely: "Because of too much pressure, my attitude yesterday was very bad, please don't care about it, brothers." Come on, eat chicken, drink cola, eat and drink to your heart's content, still good brothers. ”

"Xia Lu, let's see this outside, we are not angry with you, because we love you. Zhang Kai smiled and beat Xia Lu's chest, a real scholar, with a high IQ and high EQ.

"Thank you for your understanding. Xia Lu nodded.

"Xia Lu, is your pressure because of the exam?" Zhang Kai asked with concern.

"Nope. Xia Lu shook his head and said, "There are too many women, and women's minds are too difficult to guess, so they are troubled and stressed." ”

"Huh. Zhang Kai sneered, not knowing how to continue.

Click, click!

Strange noises rang out in the dormitory.

Qin Yibo grabbed the chicken nuggets and gnawed happily: "Eat chicken, eat chicken, good luck." ”

Du Shengyong instantly eliminated a spicy chicken leg burger, he wiped his mouth and said: "I don't like to eat foreign garbage, but I must eat the chicken that Xia Lu bought." ”

I'm not in the mood to say yes, but I'm not in the mood to say yes...... Xia Lu scolded with a smile: "I should have thought that it was a routine." ”

The chicken was also eaten, the cola was drunk, and everyone chatted and chatted, and it was natural to talk about today's exam.

"It's difficult. Qin Yibo sighed.

"It's harder than I thought it would be. Du Shengyong's face was a little solemn.

"It's okay, the teacher said that which class we are assigned to mainly depends on our subjective intentions. Zhang Kai comforted the two roommates that he felt good about himself.

"I still say the same thing, I hope that our four brothers can be assigned to the same science class. Xia Lu is also very confident in this exam, since it is an exam arranged by Hongyi Academy, it will never be a casual test, and the results will not be used as any reference. From the first day of entering this university, the scores of any exam will be recorded.