Câu 2:

a: \(x-\dfrac{1}{3}=\dfrac{5}{2}\)

=>\(x=\dfrac{5}{2}+\dfrac{1}{3}=\dfrac{15}{6}+\dfrac{2}{6}=\dfrac{17}{6}\)

b: \(\left(1-2x\right)^2=\dfrac{4}{9}\)

=>\(\left(2x-1\right)^2=\dfrac{4}{9}\)

=>\(\left[{}\begin{matrix}2x-1=\dfrac{2}{3}\\2x-1=-\dfrac{2}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{5}{3}\\2x=\dfrac{1}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{6}\\x=\dfrac{1}{6}\end{matrix}\right.\)

Câu 1:

a: \(-\dfrac{4}{3}+\dfrac{3}{2}:\dfrac{9}{4}\)

\(=\dfrac{-4}{3}+\dfrac{3}{2}\cdot\dfrac{4}{9}\)

\(=\dfrac{-4}{3}+\dfrac{2}{3}=-\dfrac{2}{3}\)

b: \(\left(\dfrac{10}{9}+\dfrac{13}{7}\right)-\left(\dfrac{19}{9}-\dfrac{1}{7}\right)\)

\(=\dfrac{10}{9}+\dfrac{13}{7}-\dfrac{19}{9}+\dfrac{1}{7}=\left(\dfrac{10}{9}-\dfrac{19}{9}\right)+\left(\dfrac{13}{7}+\dfrac{1}{7}\right)\)

=-1+2

=1

juan ko anh thịnh

ĐKXĐ: \(x\notin\left\{1;-1\right\}\)

\(\dfrac{1}{x+1}+\dfrac{2}{1-x}-\dfrac{1-5x}{x^2-1}\)

\(=\dfrac{1}{x+1}-\dfrac{2}{x-1}+\dfrac{5x-1}{\left(x-1\right)\left(x+1\right)}\)

\(=\dfrac{x-1-2\left(x+1\right)+5x-1}{\left(x-1\right)\left(x+1\right)}\)

\(=\dfrac{6x-2-2x-2}{\left(x-1\right)\left(x+1\right)}=\dfrac{4x-4}{\left(x-1\right)\left(x+1\right)}=\dfrac{4}{x+1}\)

Giá tiền của 1 cái điều hòa trong mùa hè là:

\(5000000\times\left(1+10\%\right)=5500000\left(đồng\right)\)

Giá tiền của 1 cái điều hòa trong mùa thu là:

5500000x(1-15%)=5500000x0,85=4675000(đồng)

1/5 giờ=12 phút

\(1\dfrac{1}{3}phút=80\left(giây\right)\)

7m45cm=745cm

\(\dfrac{1}{5}giờ=\dfrac{1}{5}.60\left(phút\right)=12\left(phút\right)\)

\(1\dfrac{1}{3}phút=\dfrac{4}{3}.60\left(giây\right)=80\left(giây\right)\)

\(7m45cm=700+45\left(cm\right)=745\left(cm\right)\)

\(45ha50dam=4500+500\left(m\right)=5000\left(m\right)\)

\(\dfrac{9}{2}\times x-\dfrac{3}{2}\times\left(x+2\right)=24\\ \dfrac{9}{2}\times x-\dfrac{3}{2}\times x-3=24\\ \left(\dfrac{9}{2}-\dfrac{3}{2}\right)\times x=24+3\\ 3\times x=27\\ x=27:3=9\)

Vậy x=9

\(\dfrac{9}{2}\text{x}X-\dfrac{3}{2}\text{x}\left(X+2\right)=24\)

=>\(\dfrac{9}{2}\text{x}X-\dfrac{3}{2}\text{x}-3=24\)

=>\(3xX=27\)

=>X=27:3=9

Tỉ lệ thời gian xuôi dòng so với ngược dòng là: \(\dfrac{10}{15}=\dfrac{2}{3}\)

Trên cùng khúc sông AB, thời gian và vận tốc là hai đại lượng tỉ lệ nghịch với nhau

Do đó nên tỉ lệ vận tốc xuôi dòng so với ngược dòng là: \(\dfrac{3}{2}\)

Coi vận tốc xuôi dòng có giá trị 3 phần, vận tốc ngược dòng có giá trị 2 phần

Hiệu số phần bằng nhau:

 3 - 2 = 1 (phần)

Vận tốc ca nô khi ngược dòng là:

 8 : 1 x 2 = 16 (km/giờ)

Vận tốc ca nô khi xuôi dòng là:

 8 : 1 x 3 = 24 (km /giờ)

Vận tốc dòng nước là:

  (24 - 16) : 2 = 4 (km/giờ)

Vận tốc thực ca nô là:

  24 - 4 = 20 (km/giờ)

Chiều dài khúc sông AB là:

  24 x 10 = 240 (km)

\(-\dfrac{4}{3}+\dfrac{3}{2}:\dfrac{27}{12}=\dfrac{-4}{3}+\dfrac{3}{2}\cdot\dfrac{12}{27}\)

\(=\dfrac{-4}{3}+\dfrac{3}{2}\cdot\dfrac{4}{9}=\dfrac{-4}{3}+\dfrac{2}{3}=-\dfrac{2}{3}\)

Sure, let's work through the exercises step by step.

### I. Choose the word whose pronunciation is different from that of the others.

1. **D. pour** (The others have the /aʊ/ sound, while "pour" has the /ɔ:/ sound)
2. **C. favourite** (The others have the /ai/ sound, while "favourite" has the /eɪ/ sound)
3. **B. repeat** (The others have the /ɪər/ sound, while "repeat" has the /iː/ sound)
4. **A. doctor** (The others have the /oʊ/ sound, while "doctor" has the /ɒ/ sound)

### II. Choose A, B, C, or D to complete the sentences.

1. Hoa is sitting _______________ her parents.
   - **D. between**

2. The Nile river is _______________ than the Mekong river.
   - **B. longer**

3. If the weather ____________ good, I ___________ camping with classmates.
   - **A. is / will go**

4. Hi-tech robots will be able to look _______________ children in the future.
   - **C. after**

5. The food is very _______________.
   - **B. delicious**

6. Many girls and women _______________ aerobics to keep fit.
   - **C. do**

7. Hai can _______________ boxing well.
   - **A. do**

8. In the future, we _______________ go to the moon for our holiday.
   - **B. might**

### III. Write the past and past participle form of the verbs.

1. do – **did** – **done**
2. get – **got** – **gotten/got**
3. teach – **taught** – **taught**
4. give – **gave** – **given**
5. meet – **met** – **met**
6. have – **had** – **had**
7. eat – **ate** – **eaten**
8. ride – **rode** – **ridden**
9. build – **built** – **built**
10. see – **saw** – **seen**

### IV. Supply the correct form of the verbs.

1. Nam **will buy** a new laptop tomorrow.
2. He **did not eat** fish last night.
3. Mary **studies** in the school in the afternoon.
4. Look! The bus **is coming**.
5. Her sister **is not cooking** dinner now. She **is reading**.
6. There **are** no flowers in my garden.
7. Tam and her friend always **go** to school early.
8. **Have** you **seen** a good movie yet?

### V. Arrange the words into the sentence.

1. I have been to Hanoi three times.
2. My brother is the tallest person.
3. He lives very far from his office.
4. Where did you play badminton yesterday?

### VI. Match the verbs in A with the words in B.

0. play - **f. badminton**

1. speak - **a language**
2. go - **swimming**
3. fly - **a kite**
4. have - **dinner**
5. do - **exercise**

### VII. Use words in the brackets to combine each pair of sentences below.

1. If we pollute the air, we will have breathing problems.
2. Because it is raining very hard, we will not go on a picnic tomorrow.

tại sao câu số 4 bài 1 lại chọn after v ạ?

a: Vì \(32⋮4\)

nên \(32\cdot27\cdot14⋮4\)

=>\(A⋮4\)

b: \(20⋮4\)

=>\(20\cdot43\cdot41⋮4\)

=>\(B⋮4\)

c: \(124⋮4\)

=>\(124\cdot45\cdot29⋮4\)

=>\(C⋮4\)

d: \(22\cdot2=44⋮4\)

=>\(22\cdot127\cdot2\cdot15⋮4\)

=>\(D⋮4\)

a) A = 32 . 27 . 14

= 4 . 8 . 27 . 14 chia hết cho 4

b) B = 20 . 43 . 41

= 4 . 5 . 43 . 41 chia hết cho 4

c) C = 124 . 45 . 29

= 4 . 31 . 45 . 29 chia hết cho 4

d) D = 22 . 127 . 2 . 15

= 2 . 11 . 127 . 2 . 15

= ( 2 . 2 ) . 11 . 127 . 15

= 4 . 11 . 127 . 15 chia hết cho 4

Vậy tất cả các tích trên đều chia hết cho 4

ĐKXĐ: \(x\notin\left\{0;-2;2\right\}\)

\(\dfrac{x+4}{x^2-4}-\dfrac{1}{x^2+2x}\)

\(=\dfrac{x+4}{\left(x-2\right)\left(x+2\right)}-\dfrac{1}{x\left(x+2\right)}\)

\(=\dfrac{x\left(x+4\right)-x+2}{x\left(x+2\right)\left(x-2\right)}=\dfrac{x^2+3x+2}{x\left(x+2\right)\left(x-2\right)}\)

\(=\dfrac{\left(x+2\right)\left(x+1\right)}{x\left(x+2\right)\left(x-2\right)}=\dfrac{x+1}{x\left(x-2\right)}\)