Super Learning System to Become a Master in One Second (Become Top Student In A Second)

"Qin Luo, get up and talk about your process of solving this problem." At this moment, Li Wei's "kind" words brought Qin Luo back to reality.

Denote Sn as the first n terms of the arithmetic sequence {an} and always a1=-7S3=-15

(1) Find the general term formula of {an}.

(2) Find Sn, and find the minimum value of Sn.

This is an arithmetic sequence minimum problem.

The first question is relatively simple, just to find the general term formula, but the difficulty of the second question increases suddenly.

Not only the value, but also its minimum value.

Mr. Li is creating an opportunity for me to pretend.

What a once-in-a-lifetime good teacher.

At this moment, in Qin Luo's eyes, Li Wei was no longer a black-faced evil spirit, but a little white flower with no sorrow and no injury.

Qin Luo went to the blackboard and picked up the chalk and didn't answer immediately, he fell into deep thought.

Which method should I use to force myself?

5 minutes passed, Qin Luo didn't write a word, he stood in front of the blackboard in a daze.

"Qin Luo!" Li Wei's face was ashen, and he scolded: "What are you waiting for."

"Emmm, I'm thinking of solving it that way."

"Why, you still have several methods?" Li Wei became interested. For arithmetic sequence, his high school knowledge covered one solution. He was very curious about what solution Qin Luo could "original" come up with.

"Not much, not much, just three."

"..."

"The first one." Qin Luo raised his hand and wrote a capital one on the blackboard, then quickly began to solve the problem.

"Assuming the tolerance of {an} is d, it can be seen from the question that 3a1+3d=-15"

d=2 from a1=-7

The general term formula of so {an} is an=2n-9

(2) Sn=n-8n=(n-4) from (1), so when n=4, Sn is the minimum value, and the minimum value is -16

"Second"

Without stopping, Qin Luo continued to write.

"f'(ξ)*(b-a)=f(b)-f(a)...the minimum value is -16"

"The third formula if the general term is an=2n-9..."

one two Three!

The three methods yielded the same results!

But each method is quite different.

Quiet, deadly quiet.

Of the 47 students in the entire classroom, no one spoke.

It's not that they don't want to say it, it's that they have nothing to say!

Qin Luo is a tyrannical mess, and even the content of the university is useful. Can they talk about it?

You know, knowing is one thing, and using it flexibly is another.

Qin Luo's ability to solve problems using university methods proves that he is already familiar with methods.

"In the last method, did you use the split-term cancellation method?" After a long silence, Li Wei broke the silence in the classroom.

"En." Qin Luo nodded.

"Where did you learn it?"

"Self-taught."

"Where did you learn?" Li Wei asked, the split-term elimination method, which is a university content, and is slightly covered in high school elective textbooks.

"Lagrange's Mean Value Theorem, and Ptolemy's Theorem,"

Li Wei was stunned: "Are you studying Advanced Numbers by yourself?"

"Well, but I'm studying Goldbach's conjecture recently."

With 500 Xueba points, Qin Luo coveted him.

"..." The first second, Li Wei was elated, but the next second he was speechless as if he had eaten flies.

Goldbach's conjecture is something that a high school student can study. Do you think you are Tao Zhexuan or Qiu Chengtong?