How to break into a math book

Everything in this scene pretending to be the real world is actually reminding Tu Hua of his mistakes in the opposite way.

He drew a rectangular coordinate system on paper, and then added an upward arc in the first and second quadrants, which is the image of the exponential function on the blackboard.Before entering the tribe, he and Sun Wei drew an image on the ground in the same way, and made a seemingly accurate judgment: the temperature line pointing north and south is the y-axis, and the humidity line pointing east-west is the x-axis , the first Gobi they were teleported to was the third quadrant, the desert they reached by walking north across the river was the second quadrant, and the rainforest they saw across the canyon was the first quadrant.

And the traveling route of the black people is the function image, the exponential function.

Tu Hua has always believed that this judgment process is very rigorous. Sun Wei's sensitivity is very strong. It is impossible for him to determine the x-axis and y-axis through dry, wet, cold and heat, so he has never made this judgment. There was a hint of doubt.

Until now, he firmly believes that this judgment process is correct, but the answer is wrong.Tu Hua glanced at the blackboard, and the big words "logarithmic function" were like a thunderbolt, which finally woke him up—their judgment was not wrong, what was wrong was the conditions set at the beginning.

Tu Hua held his breath and concentrated, the correct answer was ready to come out.He rotated the white paper on the table with the image of the exponential function 90 degrees to the right, the image was reversed, and a completely different image appeared on the paper.

The temperature y-axis in the north-south direction becomes the x-axis at this time, and the humidity x-axis in the east-west direction becomes the y-axis. The arc that monotonically increases in the first and second quadrants becomes an arc that monotonically decreases in the first and fourth quadrants.

This is a logarithmic function where a is greater than 0 and less than 1.

The thinking is completely clear.At the beginning, the Gobi Desert they were teleported to was not the third quadrant of the Cartesian coordinate system, but the second quadrant. They walked north, that is, went right along the x-axis, and the desert they arrived at was the first quadrant. The quadrant, going east is the rainforest encountered along the y-axis direction, which is the fourth quadrant.

According to the direction of this coordinate system, the trajectory of those black people is a logarithmic function that monotonically decreases from the first quadrant to the fourth quadrant.They subconsciously associate the Cartesian coordinate system with the map, thinking that the direction of the coordinate system and the direction of the map are the same judgment standard of "up north, down south, left west, right east". In fact, the direction of this coordinate system map is rotated to the right At 90 degrees, north is on the right, east is on the bottom, south is on the left, and west is on the top.

Then everything that Tu Hua encountered in this new scene can be explained, because the answer he gave is an exponential function opposite to the correct answer, so everything in this world is turned upside down.

The deskmate who hated English the most fell in love with memorizing words; I, who never failed in math, got full marks every time; Mr. X, who was obviously married to me, actually said that he married me.

There is also the problem of the math teacher, which is obviously an image of an exponential function, but it is corrected to a logarithmic function.

Everything in this world is reminding Tu Hua in the form of inverse functions, how can he get the correct answer.

After figuring out the ins and outs, Tu Hua felt a lot more relaxed. With 10 hours left before the 4 hours stipulated by Mr. X, he took out the ghost stone from the system backpack, stood up and walked out.

The math teacher held up the chalk and looked at the proud students who were free to enter and leave the classroom with a dazed face. He saw that Tu Hua was walking out like a school bully who often skipped classes, and made a chic gesture of waving: "Take care of yours!" class!"

Tu Hua came to the playground, took out the ghost stone, and was prompted by the system【Are you sure you want to use the ghost stone to revive and answer the question? ], select the OK key.

The entire campus seemed to be trapped in a vortex of distorted time and space, and the surrounding scenes changed rapidly. In the blink of an eye, he returned to the dimly lit thatched hut.Surrounded by the setting of the wedding night in the bridal chamber, although simple, the ambiguous light still conveys a charming atmosphere.

The sounds of the natives singing and dancing could be faintly heard outside, and the ghost stone he held in his hand had now turned back into the function crystal with a light blue thin line in the middle.Everything seemed like a dream, Mr. X was still wearing the animal skin and sitting opposite him, looking at him with a smile on his face: "Have you thought about it?"

Tu Hua's pupils shrank suddenly, and he kept taking deep breaths.The information in his mind quickly intertwined and collided at this moment, subverting the new answer he got again.The arc without coordinate quadrant in the function crystal is still emitting blue light, it seems that it can't wait for Tu Hua to pronounce its name.

At that moment, Tu Hua seemed to understand something.He looked up at Mr. X, and said in a daze: "The Nether Stone has already been handed over to the chief, so there is no resurrection at all, right?"

"You are very smart." Mr. X stared at him meaningfully, "but I can't reveal any details to you, you just need to tell me the answer."

His expression was very gentle, without any elements of anxiety or urging, but it made Tu Hua's heart anxious involuntarily.He always thought that Mr. X was different from other NPCs. He met Miss Y, witches and even black people in the desert. They all prevented the challenger from passing the level. Although they were similar to real people, they were cold and emotionless most of the time. of.But Mr. X is different from them, he always exudes a warm and reassuring feeling.

At this moment, he was flustered, not sure if Mr. X was hiding a knife in his smile.He hesitated a little, and asked after a while, "Do you want me to clear the customs?"

After hearing his question, Mr. X was obviously stunned for a moment, and he felt how stupid his question was when he said it out of his mouth. He asked an NPC if he wanted to let him pass the level?He is a character in the game, he has no thought or emotion, just a program composed of a piece of code.He treats every challenger with the same attitude, he will only continue to set up difficulties in the level...

"think."

Mr. X's answer completely disrupted Tu Hua's thoughts of finally getting on the right track. Not surprisingly, he blushed again. Mr. X didn't seem to realize that the little boy in front of him was blushing by an NPC character, and continued to add embellishments: "I appreciate you very much."

Tu Hua glanced at him, then hurriedly avoided his gaze, got up from the blanket, paced around the room a few times, and finally said, "I've figured out the answer."

Mr. X raised his head and motioned for him to continue.

Tu Hua reverently raised the function crystal over his head, his eyes sparkled: "Exponential or logarithmic function."

Mr. X finally showed a satisfied smile on his face: "Two functions? What do you think?"

Tu Hua suddenly laughed, the previous shyness was swept away, and there was still a little arrogance in his eyes: "You told me."

Mr. X showed a surprised expression.

Tu Hua squatted in front of him, with curved eyes: "At first, I was afraid that you would be like other NPCs, deliberately not letting me pass the level, and I was not sure whether the favorability item of Mr. X was useful, so I asked Do you want me to pass the customs?"

"You said you admired me." Tu Hua raised his lips, "This is actually an affirmative answer, which indirectly proves that favorability items are useful. Although you didn't give me a hint, at least it won't hinder me from clearing the level."

"Remember the first sentence I asked you? 'The Nether Stone has been handed over to the chief, so there is no resurrection, right?'" Tu Hua analyzed, "Your answer is 'You are very smart'. If You want me to pass the level, this sentence is an affirmation of the question I asked."

"The ghost stone doesn't have two functions at all. It doesn't have the function of resurrection, it just serves as a recommendation for the chief. But if it can't revive me, why did I get the chance to be resurrected even though I answered the question wrongly? Have you been teleported to another scene?"

Tu Hua looked at him with burning eyes: "Because that pseudo-real scene is not a resurrection scene at all, but a necessary plot for this [Function Level] mission."

"From the time the four of us entered this level, all the conditions and hints we got were guiding us to make judgments about the type of function. The answer to the exponential function was not wrong, it was just not comprehensive enough. The first Gobi Desert we reached , it can be judged that it is the third quadrant, or it can be judged that it is the first, second and fourth quadrants. If we analyze it accurately, we should be able to get four answers."

"When the Gobi Desert is regarded as the third quadrant, the trajectory is a monotonically increasing function in the first and second quadrants; when the Gobi Desert is regarded as the second quadrant, the trajectory is a monotonically decreasing function in the first and fourth quadrants; when it is When used as the first quadrant, the trajectory is a monotonically increasing function in the third and fourth quadrants; when it is used as the fourth quadrant, the image becomes a monotonically decreasing function in the second and third quadrants."

"These four possibilities exist, and there is no evidence to suggest that any of them is wrong. I only answer one, and I will be transported to that pseudo-real scene, no matter what I answer is the index. The function is still a logarithmic function." Tu Hua looked serious, "How can the same mistake be made a second time?"

"So considering the scope of high school mathematics and the definition of functions, I think the answer is 'exponential or logarithmic function.'" Tu Hua was full of confidence, waiting for the system to make a judgment.

【Ding--】

[Challengers Tu Hua, Wang Boyu, Sun Wei, and Tang Bo passed the main level of the function and are about to enter the next level, the trigonometric function level. 】

success!

Tu Hua couldn't hide his joy. Since they had already cleared the level, the scene of this level was about to disappear, but Mr. X in front of him remained motionless.He came over suddenly and stood in front of Tu Hua, with an unpredictable expression on his face: "There is one thing you said wrong."

Tu Hua looked at him in astonishment.

Mr. X stroked Tuhua's hair with his hand, and said with a soft smile, "I admire you, and it has nothing to do with the favorability item."

Before Tu Hua could react, Mr. X disappeared in the blink of an eye.

Tu Hua stared blankly at the direction in which he disappeared, feeling his heart beat faster again in an instant.He covered his chest with one hand, and couldn't help thinking: Is he... being teased by this NPC again?

The thatched huts disappeared, the surrounding dense rainforest disappeared, and the singing and dancing indigenous people also disappeared.Tu Hua turned his head and saw his three partners running towards him excitedly.The body suddenly lost weight, and the next moment, the four of them were teleported out of the checkpoint together and returned to the original campus map.

It was still the same school, but this time there were very few people, only a few people wandering in the teaching building.The prompt beeps, and the system screen pops up:

[Welcome to Trigonometric Functions. 】

Tu Hua clicked to check the number of people in the level. The system showed that the number of people entering this level was less than 1000, and the number of people was slowly rising, which proved that most people were still trapped in the previous function level.While they were waiting for the release of the trigonometric function to close the main task, a prompt popped up on Tuhua's screen:

[Challenger Tuhua gets the props Mr. X's favorability +10]

[Currently, the favorability has reached 25, do you want to exchange for a new item: Mr. X's company? 】

The author has something to say: If it is difficult to understand the text, interested babies can draw a function image on paper like painting~

ps: When a is equal, the exponential function and the logarithmic function are inverse functions of each other.The exponential function a in this level is greater than 1, while the logarithmic function a is greater than 0 and less than 1. These two functions are not inverse functions.The definition of the inverse function is used in the middle, just to remind Tuhua to think of the logarithmic function~~