I really just want to be a scholar

Chapter 31 By the way, treasure it for a lifetime
Qin Ke could see the idea of ​​solving the problem at a glance, and he quickly wrote in his notebook:

"This question is not difficult, the key lies in changing thinking. You see, there are two parameters a and b on it, and there are many constraints, which are not intuitive, and it seems a bit difficult to start. Here we can use the solution of 'combination of numbers and shapes' Problem-solving strategy. Do you know this problem-solving strategy?"

"The teacher said it in the training camp." Ning Qingyun nodded, but there was still a little confusion in his eyes, as if he didn't understand how to apply it to this topic.

It is rare to see such a look on the girl who is always cold and proud. It is inexplicably weak and cute, which makes people have a strong desire to protect.

Girl, why do you feel that this guy is a little too cute tonight!
Qin Ke restrained his mind and continued to write calmly without looking sideways:

"Numbers and shapes can both reflect the attributes of things, and the combination of numbers and shapes can solve mathematical problems through the correspondence and transformation between numbers and shapes."

"Specifically, when solving problems, it is to concretely quantify the problems of graphic nature with the help of deduction of quantitative relations, or to visually visualize the problems of quantitative relations with the help of geometric background, and to solve problems by "using shapes to help numbers" or "using numbers to solve problems". Form', which simplifies complex questions and makes abstract questions concrete, and is most suitable for such question types."

He didn't wait for Ning Qingyun's answer, and directly wrote the solution to the question:
“设一个方程f(x)= X^2+ax+2b-2，由已知可得f(0)大于0，f(1)小于0，f(2)大于0，这样我们就可以得出三个不等式了：

b is greater than 1, a+2b is less than 1, a+b is greater than -1,

Then we directly draw the area satisfying these three inequalities in the Cartesian coordinate plane aOb. "

Qin Ke drew a Cartesian coordinate plan and drew a few straight lines.

"Look, so we can see that the slope of the line connecting each point (a, b) to (1, 4) in the region where all three inequalities are satisfied is exactly (b-4)/(a- 1), so that the answer can be easily obtained, (b-4)/(a-1)∈(1/2, 3/2)."

"This is the problem-solving strategy of the combination of numbers and shapes. You only need to convert the conditions in the title into f(0) greater than 0, f(1) less than 0, and f(2) greater than 0, and then transform this relatively abstract quantitative relationship into For the intuitive positional relationship of geometric figures, the problem can be simplified immediately."

"There are many similar question types, I will write a few questions for you..."

Ning Qingyun stared blankly at Qin Ke, who was writing hard and earnestly, and once again sighed in his heart, this guy's clear thinking and quick thinking were the only things he had ever seen in his life.

Especially his brain, which is truly a genius's brain, is more than one grade higher than that of an ordinary person like himself.

He thought of the solution to this difficult problem that he had been pondering for more than ten minutes without thinking of a clue, and he knew that he could adopt the most appropriate strategy of "combining numbers and shapes" to solve the problem!
Ning Qingyun's own foundation is extremely solid. Listening to Qin Ke's detailed explanation in the notebook again with examples, he quickly grasped the key points. She is confident that she can form the transformation between "number" and "shape" in just a dozen seconds, and continue to solve the problem according to Qin Ke's thinking.

Ning Qingyun couldn't help but feel lucky for her decision just now. Although she had to spend time teaching Qin Ke English, she probably learned more from this guy.

"Okay..." The girl reached out and pressed Qin Ke's pen.

Qin Ke raised his head unexpectedly.

Ning Qingyun wrote in the notebook: "It's too hard for you to write like this. You can explain it to me in detail next time when it's convenient for you to talk."

Qin Ke shook his sore wrist, but he didn't expect this guy to be considerate.

"Row."

"I have English notes for the first year of high school in the dormitory, and I will bring them to you tomorrow..."

"Thank you, school committee, I love reading your school committee secrets the most! I can't wait to hug you to sleep."

Ning Qingyun blushed slightly, and said angrily: "Jingai is talking nonsense, I will lend you your notebook, you can't sleep with it in your arms."

Qin Ke was speechless, girl, I'm joking, it's just an exaggerated rhetoric, I'm not a pervert.

Qin Ke finally discovered that this guy's sense of humor is very lacking, he will take any joke seriously, and he is especially easy to be laughed at, and I don't know if no one teased her before or she is born with a low sense of humor.

Ning Qingyun wrote again: "Oh, by the way, Mr. Zheng said when the math class was over, we will not come to the classroom for self-study tomorrow, but go to the mathematics research room in Building B to participate in the Mathematical Olympiad intensive training class. Remember?"

"remember."

"The training for the Olympiad still starts at [-]:[-] in the morning, so don't be late."

Qin Ke made an OK gesture, looked at his notebook, and found that he had written two full pages, all of which were conversations between himself and Ning Qingyun.

He couldn't help feeling a little bit emotional.When I first sat at the same table with this guy, I probably never dreamed that I would "talk" to her in class like this for two pages, right?
"By the way, school committee, is the little note you gave me in the evening still there?"

"I haven't had time to throw it away yet. What's the matter?"

Ning Qingyun hesitated for a moment, but took out the crumpled note from her schoolbag.

"Can you give it to me?"

"What are you coming for?"

Qin Ke didn't answer, and stretched out his hand to snatch it from her.

"Hey, you bastard... can you stop robbing me all the time, you were a robber in your last life!" Ning Qingyun felt that Qin Ke's fingers slipped over her little hand just now, and her little face suddenly turned red, feeling ashamed. He glared at Qin Ke angrily.

"You have discovered all of this, and I also think I am quite suitable to be a robber." Qin Ke carefully flattened the small note, put it in the book, and then smiled and answered with a mouthful of white teeth, writing in correct fonts :
"I plan to use this note as a motivation to spur myself to study hard, read it every day, keep it in my heart, and cherish it for a lifetime."

Ning Qingyun's heartbeat was inexplicably a little messy. She brushed the hair on her sideburns to cover her little ears that were a little hot for some reason. road:

"You are all bored, study hard! Memorize all the English words in the textbook first!"

"Understood." Qin Ke actually only wanted to write the first sentence "as a motivation to whip himself to study hard" to please Ning Qingyun, but after seeing her cute and embarrassed expression, he somehow added the last three sentences .

At this time, he also regretted a little, if he really annoyed this very tender-skinned school committee member, it would be self-defeating.

Fortunately, Ning Qingyun didn't explode now, so Qin Ke hurriedly put on a serious study, and took out his English textbook to memorize words.

Seeing his appearance as a cute baby, Ning Qingyun couldn't help but twitched the corners of her mouth again. She ignored Qin Ke again, took out the "dialogue book" placed in the middle of the table, and read the explanation written by Qin Ke seriously again. Question process and subsequent example explanations.

Under the light, on the white paper, Qin Ke's correct handwriting looked very comfortable.

(End of this chapter)