Bài 17: Viết dưới dạng tích các tổng sau:

1/ ab + ac

2/ ab – ac + ad

3/ ax – bx – cx + dx

4/ a(b + c) – d(b + c)

5/ ac – ad + bc – bd

6/ ax + by + bx + ay

Bài 4: Tính tổng
1/ 1 + (-2) + 3 + (-4) + . . . + 19 + (-20)
2/ 1 – 2 + 3 – 4 + . . . + 99 – 100
3/ 2 – 4 + 6 – 8 + . . . + 48 – 50
4/ – 1 + 3 – 5 + 7 - . . . . + 97 – 99
5/ 1 + 2 – 3 – 4 + . . . . + 97 + 98 – 99 - 100
Nhanh giúp mk nha !!!

Điền từ nghĩ thích hợp :

A, .Mrs Chi and her children.................in the garden. She has a very beautiful garden behind her house. There are a ...............of flowers in the.......................She usually puts....................flowers............the sitting ...............Mrs Chi has .................friends ............London. Her friends are .........to visit her family next week. Mrs Chi often gives them a ..............of flowers when they go home from her house.

B, Miss Moreys lives in a suburb of London and she (1)________ English at a school. She has a lot of students. They (2)________ from different countries. Miss Moreys usually (3)_______ breakfast at 8 a.m. (4)_______ breakfast, she has some bread, two eggs and a cup of coffee. Then she goes to work. She usually goes by car but sometimes she goes (5)_______ her bike. She comes back home at 4 p.m. In the evening she (6)________ TV or listens to (7) ________ radio. She usually goes to (8)______ at 10 p.m.

a) A = 1 + 2 + 2² + 2³ + ... + 2⁶⁷ 

2A = 2 + 2² + 2³ + 2⁴ + ... + 2⁶⁸

2A - A = ( 2 + 2² + 2³ + 2⁴ + ... + 2⁶⁸ ) - ( 1 + 2 + 2² + 2³ + ... + 2⁶⁷ )

A = 2⁶⁸ - 1

b) B = 3⁰ + 3¹ + 3² + ... + 3⁵¹

3B = 3 + 3² + 3³ + ... + 3⁵²

3B - B = ( 3 + 3² + 3³ + ... + 3⁵² ) - ( 3⁰ + 3¹ + 3² + ... + 3⁵¹ )

2B = 3⁵² - 3⁰

B = ( 3⁵² - 3⁰ ) : 2

9.He goes to Hue by plane once a month .
=>He takes.................................................

10.They travel to work by car
=>They drive..............................................

11.What is the price of these apples?
=>How......................................................................

12.What is the width of this lake ?
=>How..............................................................

13.It is often cold in the winter.
=>The weather...............................................................................

14, Linh is the eldest of the three sisters .
=> Linh has ..................................................................

15, Hao is the best in his class .
=>No one in Hao’s ...........................................................................................

16.Whose book is this?
=> Who ……………………………………………………………………?

17. How heavy are you ?
=> How much does………………………………………………………….?

18. How heavy are you?
=>How much………………………………………………………………..?

19. Mr. Ba is the owner of this house.
=>This house………………………………………………………….

20. No one in our class is as tall as Nam .
=>Nam is the ……………………………………………………

21. There are 40 monkeys in the cage .

=>The cage ……………………………………………………………………

22. It is one fifty .

=>It is ten …………………………………………………………………….

Sửa lỗi sai :

2. The Browns is travelling to Hanoi by plane..................

3.My house is between those four houses.................

4.Chi lives on 78 Dinh Tien Hoang Street......................

5.A chicken is my favorite drink...............

6.There are fish and vegetables in our dinner..............

7.Hoa needs two bar of soaps.....................

8.I'd like half dozen eggs.............................

9.I am going to stay to the Huu Nghi Hotel........................

10.How often do Chi goes to the movies?....................

11.My name is Bruce and I am from Australian.........................

12.HoChiMinh City has a population 3.5 million............................

13.Hanoi is more big than HaiPhong.........................

14.There is lots rain in Vietnam............................

15.How much eggs do the chickens produce?......................

16.You shouldn't to turn off the lights when you don't need it.........................

17.The population of the world are growing.....................

18.Pestronas Twin Towers in Kuala Lumpur, Malaysia, is taller building in the world................