Teacher Xu, Please Take Care of the Reckless Students in Your Class

Chen Jianhua, "This question is not bad."

Zhang Ruiyun, "!!!"

"Mr. Chen, why did you come out! This, this, this..."

Chen Jianhua joked, "Good question, why don't you give me this old man to watch?"

Zhang Ruiyun was trembling with fright, "Mr. Chen, what are you talking about! I'm just afraid that the title is not good, I make a mistake, and make trouble!"

He knew very well that no matter how big things in the group were, they wouldn't attract the attention of the old professor, but as soon as this question was posted in the group today, the old professor bubbled up.

Another classmate in the group said, "Mr. Chen, didn't you say that you are retired, so you don't care about mathematics?"

Chen Jianhua, "When I see a good topic, my heart is itching."

It is enough to see how seriously Chen Jianhua takes this question.

This is what Zhu Ruiyun never expected!

"Ruiyun! Those who asked this question should take part in the college entrance examination, right?"

Many people followed suit, "It must be the teacher of the college entrance examination group!"

"Even the teacher of the paper-making group spends a lot of time on this question!"

"At least a week!"

"Conservative estimate! Give it to me anyway, I can't think of it so clever!"

Zhang Ruiyun pouted, looking at what everyone was discussing on the phone, and he was even more at a loss.

"It was impossible for Mr. Zhao to show off his own questions before. The reason why he took it out this time is really out of anger."

"So it's impossible for Xu Heng to see the title in advance!"

"But this is unscientific! It's too mysterious!"

"Even if he starts to think after seeing the question, it doesn't take fifteen minutes for him to think of the second question next?"

"And the level is so high!"

Just when Zhang Ruiyun was wondering, someone in the group @ him and asked, "What is the answer? The difference between b minus a divided by 2, right?"

How does Zhang Ruiyun know if it's right!

He got goosebumps all over, jumped, stood up, and rushed out of the office.

When I came to the door of Class 30, I was about to knock on the door, but saw Wei Minghai writing the problem-solving ideas on the blackboard.

solution:

If |p1-p2|>log(3)2, discuss separately

（1）当p1-p2＞log（3）2时，f1（x）……

……

Since f(a) = f(b), so...

……

f（x）在区间[a，b]上的单调增区间的长度和b-p1+{（p1+p2-log（3）2）/2}-p2=b-（p1+p2+log（3）2）/2=b-(a+b)2=（b-a）/2

(2) When p2-p1>log?2...

……

The final result is still (ba)/2!

It is densely packed and filled with writing on the entire blackboard!

Rumble!

Like five thunders pounding the top, as if there was an electric current pouring straight down, making Zhang Ruiyun stupid.

Wei Minghai, "To sum up, the sum of the lengths of f(x) in the interval [a, b] of monotonic equal intervals is the difference of ba 2/[-]. Teacher Xu, is my answer correct?"

Xu Heng nodded slowly.

Boom!Boom!

Zhang Ruiyun's legs were paralyzed and he couldn't stand still.

As a student, Wei Minghai gave the correct answer in such a short time!

With his fellow senior mathematicians in the group, it's almost time to figure it out!

"genius!"

"Absolute genius!"

"This teacher Xu is amazing..."

Just when Zhang Ruiyun admitted in the group that the answer was correct, and the students in the group were discussing that the solution to this question was a bit complicated...

Xu Heng said to the whole class, "This question doesn't need to be so complicated, Wei Minghai, let me remind you, the absolute value function."

A word to wake up the dreamer!