Chapter 65: Holding the grass, there is someone behind

After reading the test rules, the test papers were quickly distributed to everyone.
The introduction to the test paper is divided into 3 questions.
In the first question, let A and B be two points on the hyperbola x²-y²/2=z, point N(1,2) is the midpoint of the line segment AB, and the perpendicular bisector of the line segment AB intersects the hyperbola at the two points CD .
Please determine the value range of z.
"Damn it, should it be so difficult?"
"Teacher, you want to kill us, right?"
"I don't know how to coach this question."
"..."
Just seeing the first question, there were wailing in the entire auditorium.
This question seems to be very short, but the knowledge used is extremely rich.
It covers almost all the knowledge points of the entire high school.
Even if the people sitting are all at the level of academic masters, they can't help but scratch their heads when they get this question.
It's hard, it's too hard.
"Hey, who wrote this question, isn't this deliberately scolding?"
Qin Luo saw through everything at a glance, and without too much hesitation, he just lifted his pen and started to do it!
Suppose the equation of AB is: y=k(x-1)+2, bring in the hyperbolic equation...
……So the value range of z is (-1,0) U (0, +∞).
Qin Luofen wrote about the problem-solving process, and it only took him 3 minutes until now.
"Take 10 points." Qin Luo took a long sigh of relief and burned many brain cells.
After checking the accuracy, Qin Luo raised his head and looked around.
A boy on the left was trembling all over, and a the right was biting a pen and sweating... As far as Qin Luo's eyes could be, there was not a single pen.
"..." Is it really that difficult? Qin Luo didn't think so.
Suddenly, the corner of Qin Luo's eyes was closed, and he saw Bai Chong sitting in the corner.
Unlike others, Bai Chong is struggling to write.
A black gel pen drew beautiful arcs in his hand, and the answer was instantly on the paper in the next instant.
Hmm, to be able to be a student of Chengyu Seventh Middle School, there are really two brushes.
But Qin Luo didn't care. Bai Chong had two brushes, but he had dozens of them.
What surprised Qin Luo was that Lin Shanshan was also writing quickly.
Well, it seems that I do have the potential to be a teacher. In just a few days, I turned the scumbag into a tyrant.
Suddenly, Qin Luo only felt his eyes dark, and looked up: "Hold the grass, someone!"
I saw a serious-faced invigilator in Chinese tunic, staring at him intently.
The burning eyes seemed to melt him in the next second.
"What to see, hurry up and do the question." Feng Huadong said coldly.
Feng Huadong, the invigilator this time, is also the president of the Southwestern Provincial Federation of Numbers.
"...Teacher, people are scary but scary to death."
"Scared you to death? You almost scared us to death." Feng Huadong thought.
Zhou's conjecture was that a problem that had troubled mathematics for more than ten years was solved by a high school student. When he heard the news, he was almost scared to death.
No one could have imagined that a student who was still in high school could prove Zhou's conjecture.
I scared you to death? Ha ha... funny.
"Hurry up and do the question!" Li shouted, and Feng Huadong turned and left.
"Are the current invigilators so fierce?" Qin Luo shook his head and devoted himself to solving problems again.
A few minutes later, Qin Luo once again began to write quickly.