bạn cho ngắn đi

Máy bay được phát minh vào năm: 1886+7=1893 vào thế kỉ 19

Ô tô được phát minh vào năm 1886 thế kỉ 19

Đầu xe lửa được phát minh vào năm: 1893-9=1794 vào thế kỉ 18

Exercise 4; Fill in the blank with ONE word.

 1. She likes writing stories. She wants to be a/an ……writer………………………

2. My brother wants to fly a plane. He’d like to become a/an ……pilot…………………

3. She wants to teach children. She wants to become a/ an…teacher………………………..

4. Nam likes drawing and designing buildings. He would like to be a/ an

……architect……………………………when he grows up

5. My cousin enjoys playing football. He wants to become a /an …footballer…………………..

6. He’d like to fly in space and work with other people in a spaceship. He’d like to be

 a / an…astronaut………………………

7. She would like to look after patients. She would like to be a /an…nurse……………….

8. My daughter likes singing. She would like to be a/ an……singer………………….

writer

pilot

teacher

architect

footballer

astronaut

nurse

singer

 Trung: What would you (1) …………like…………………….to be in the future?

Huong: I would like to be a (2)………………teacher………………………………..

Trung: Why?

Huong: (3)……………because………………………………. I would like to teach young children.

Trung: Working (4)…………in………………………a teacher is hard work.

Huong: Yes, I know. But it is a rewarding job. How about you?

Trung: I would like to become a (5)…………footballer………………………because I like playing soccer so much.

https://lazi.vn/group/d/17374/hoi-ngot-ngao

Đặt tổng là A = 1 + 2 + 2^2 + 2^3 + ... + 2^2002 = 1 + 2 + B 
Kể từ số hạng 2^2 đến 2^2002 có 2001 số hạng mà nhóm ba số hạng liên tiếp ta được một số chia hết cho 7 
Do đó B = 2^2 + 2^3 + 2^4 + ... + 2^2000 + 2^2001 + 2^2002 
= 2^2 (1 + 2 + 2^2) + ... + 2^2000 (1 + 2 + 2^2) 
= 2^2. 7 + 2^5 . 7 + ... + 2^2000. 7 
=> B chia hết cho 7 
Vậy A = 3 + B 
nên A chia 7 dư 3

Tìm x :
2/2.4 + 2/4.6 +....+ 2/x(x+2) = 4/9
=> 1/2 - 1/4 + 1/4 - 1/6 + ...+ 1/x - 1/(x + 2) = 4/9
=> 1/2 - 1/(x + 2) = 4/9
=> 1/(x + 2) = 1/18
=> x + 2 = 18
=> x = 16