(x+2)(x-2) - (x-4)(x+1)

=(x²-4)-(x²+x-4x-4)

=x²-4-x²-x+4x+4

=3x

Bài làm 

\(\left(x+2\right)\left(x-2\right)-\left(x-4\right)\left(x+1\right)\)

\(=x^2-4-\left(x^2+x-4x-4\right)\)

\(=x^2-4-x^2+3x+4=3x\)

TRẢ LỜI:

Thực hiện phép chia:

2x3 – 3x2 + x + a chia hết cho x + 2

⇔ số dư = a – 30 = 0

⇔ a = 30.

Cách 2: Phân tích 2x3 – 3x2 + x + a thành nhân tử có chứa x + 2.

2x3 – 3x2 + x + a

= 2x3 + 4x2 – 7x2 – 14x + 15x + 30 + a – 30

(Tách -3x2 = 4x2 – 7x2; x = -14x + 15x)

= 2x2(x + 2) – 7x(x + 2) + 15(x + 2) + a – 30

= (2x2 – 7x + 15)(x + 2) + a – 30

2x3 – 3x2 + x + a chia hết cho x + 2 ⇔ a – 30 = 0 ⇔ a = 30

x thôi sao 4x

đa thức  2x³ - x² + 4x + a chia hết cho đa thức x + 2 khi  - 5x mũ 14x+a - 14x+28=0

                                                                                                                a  -      28  = 0

                                                                                                                a               =0 +28

                                                                                                                a                =28

 2x³ - x² + 4x + a : x+2 =2x mũ 2 -5x+14  

good luck!

SACH GHIAO KHOA TRANG (77)

Bài làm 

\(24=\frac{1}{2}.x.10\Leftrightarrow24=5x\)

\(\Leftrightarrow x=\frac{24}{5}\)

Ta có : \(A=12xyz:3xyz=4\)

Hoặc có thể làm theo cách khác :P

Thay x = 2 ; y = 4 ; z = 2018

Suy ra : \(\frac{12.2.4.2018}{3.2.4.2018}=4\)

Vậy giá trị biểu thức A = 4 

 * Mấy câu bên trên khó nhìn quá ạ ~

B. Read the passage carefully then answer the questions below:

Once upon a time three was a young girl called Cinderella. Cinderella was living happily with her family when her mother died. Her father married an evil widow with two daughters. Cinderella's stepmother and two stepsisters mistreated her. She had to wear old clothes and work hard while the sisters wore fancy clothes and had fun. A good fairy helped Cinderella. Shu turned Cinderella's old dress into a beautiful gown. Cinderella went to a party and a handsome prince politely invited her to dance with him. He fell in love with her wanted to find out who she was. Cinderella left the party in a hurry and didn't tell the prince her name. But she left a glass slipper, and the prince used that to find her. They got married and lived happily ever after.

* Questions:

1. What did Cinderella's father do when his wife died? .

-  He married an evil widow with two daughters

2. How did Cinderella's stepmother and two stepsisters treat her?

- Cinderella's stepmother and two stepsisters mistreated her

3. Who turned Cinderella's old clothes into a beautiful gown?

- A good fairy

4. What did the prince use to find Cinderella? 

- The prince used a glass slipper to find Cinderella

 PART V. WRITING: Question 1: Rearrange the given words to complete the sentence.

1. festival / in / Viet Nam / Tet / is / the / most / important / 

-> Tet is the most important festival in Viet Nam 

2. because / they / can / Children / / Tet / receive / lucky / money /

-> Children li ke Tet because they can receive lucky money

Question 1: Rewrite or combine the sentences, using the suggested words.

1. Mr Lamwas very busy; however, he spent the whole day at the La Mat Village festival.

=> Although. Mr. Lam very busy ,he spent the whole day at the La Mat Village festival. 

2. I love listening to music.

=> I fancy listening to music. 

3. You are advised not to wear shorts when going to pagodas.

=> You should not wear shorts when going to pagodas. 

4. My house is smaller than your house.

=> Your house is bigger than my house

* Chắc là đúng hết đấy ạ . Lần sau bạn post tách ra nhé ! để thế này khó nhìn và dài nên mọi người không giúp đâu .

1. Choose the world A, B, C or D whose s̲t̲r̲e̲s̲s̲ ̲p̲a̲t̲t̲r̲e̲n̲ is different from the others.

A. minority B. ethnic C. tradition D. religion

2. Choose the world A, B, C or D whose u̲n̲d̲e̲r̲l̲i̲n̲e̲d̲ ̲p̲a̲r̲t̲ is pronounced differently from the others

. A. live̲d̲ B. populate̲d̲ C. harveste̲d̲ D. loade̲d̲

II. Choose the best answer among A, B, C or D to complete the sentences.

1. Chọn từ có phần gạch dưới cần được sửa lỗi.

Vietnam i̲s̲ a̲n̲ m̲u̲l̲t̲i̲c̲u̲l̲t̲u̲r̲a̲l̲ country with 5̲4̲ ethnic groups. => a

A. is B. an C.mulultural D. 54

2. The whole family ________with tradition by spending the New Year's Eve abroad

. A. went B. broke C. followed D. kept

3. In Viet Nam, you________ use only the first name to address people older than you.

A. should B. must C. have to D. shouldn't

4. Lang Lieu couldn't buy any special food________ he was very poor.

A. although B. when C. while D. because

III. Give the correct tense/ form of the words in brackets.

1. They detest (get)___getting_____ up early in the morning.

2. The Tay people live mostly in the___mountainous_____ regions in the north of Viet Nam(MOUNTAIN) IV. READING:

A. Read the passage and complete it with the words given: traditions, means, according, however, therefore. The tradition of birthday parties started a long time ago. People thought there was a special danger from evil spirits on birthdays;(1)_however_____, friends and family came together to bring good thoughts and wishes and even presents. There are some different(2)____traditions____ in different countries around the word. In Viet Nam, on a child's first birthday, family members put many things on the floor around the child for him or her to choose. (3)____according____ to tradition, the first thing the child picks up will tell us his or her future job. In some countries, a 21 st birthday cake is sometimes in a shape of a key. The key (4)_____.means___ that the young person is now old enough to leave and build up to their own family at any time they want to. There is usually a special party on these birthdays.