Ta có:

(3n + 10)$⋮(n\; -\; 1)$

⇒ [(3n - 3) + 13]$⋮(n\; -\; 1)$

⇒ [3(n - 1) + 13]$⋮(n\; -\; 1)$

$Vì$3(n - 1)$⋮(n\; -\; 1)\; nên\; để$[3(n - 1) + 13]$⋮(n\; -\; 1)\; thì\; 13⋮(n\; -\; 1)$

⇒ n - 1 ∈ Ư(13)

⇒ n - 1 ∈ {1; -1; 13; -13}

⇒ n ∈ {2; 0; 14; -12}

Mà n là số nguyên dương

⇒ n ∈ {2; 14}

Vậy tập hợp A các số nguyên dương n thỏa mãn (3n + 10)$⋮(n\; -\; 1)\; là:$

$A\; =\; \{2;\; 14\}$

Gọi số hàng ở khoảng cách 1500m là a, số hàng ở khoảng cách 2000m là b, số hàng ở khoảng cách 3000m là c.

Theo bài ra ta có:

\(\frac{a}{\frac{1}{1500}}=\frac{b}{\frac{1}{2000}}=\frac{c}{\frac{1}{3000}}\) và  a + b + c = 1530 

Áp dụng tính chất dãy tỉ số bằng nhau, có:

\(\frac{a}{\frac{1}{1500}}=\frac{b}{\frac{1}{2000}}=\frac{c}{\frac{1}{3000}}=\frac{a+b+c}{\frac{1}{1500}+\frac{1}{2000}+\frac{1}{3000}}=\frac{1530}{\frac{12}{10000}}=1275000\)

Từ đây tìm a,b,c   

1.Will they go to supermarket tomorrow - Yes, they ... will

A.0 B.tomorrow C.tell D.are

2.What/ you/ are/ doing/ now/ - they're/ skipping rope

→ What are you doing now? - They're skipping rope

3.She's ill so she can't go to school today

4.My uncle/ vegetable/ to the/ market/ takes/ always

→ My uncle always takes vegetables to the market.

5.at twelve o' clock/ walks home/ his sister/ He/ and has lunch with

→ He walks home at twelve o'clock and has lunch with his sister.

6.a quarter/ to seven/ I/ at/ go to school

→ I go to school at a quarter to seven.

7.Lien/ hard/ worker/ is/ a

→ Lien is a hard worker.

8.Mary/ noise/ always/ makes/ in the class

→ Mary always makes noise in the class

9.They are going to stay in Hue for a week

10.Johnny is from Britain. He speaks English.

1.Jim and Sam are interested in Arts. They say it is very interesting.

2.What time does your family have breakfast? - At 7 o' clock.

3.The museum is behind the park.

4.Look! The boys are talking about the football match.

5.I have two brother. ... names are Minh and Tung.

A.His B.Their C.They D.Theirs

6.Does Tom play badminton at 4pm?

7.The writer of the book you're reading is in African

8.My sister has got some friends from Germany( nước Đức)

9.After dinner, my mother checks my homework before bedtime.

10.Fifty-five plus twenty-two equals seventy-seven

11.What is your kitchen like?

12.I work from six o' clock in the morning until three in the afternoon.

13.The students played different sports such as badminton, chess and hide-and-seek.

14.I am having a birthday party with my friends.

15. What is his nationality? - He is Australian( Nước Úc )

1.What's the weather like in the summer?

2.What's the matter? I have a fever.

3.The festival was held in the park near our school.

4.Sally doesn't want to eat hamburgers any more.

5. Were you at Ha Long Bay last weekend?

6.Do you have many friends?

7.I need some stamps. Where is the post office?

8.I can't go on a trip because we are very busy.

9.What time do you get up? - I get up at 7.am.

10.Everyday, I clean my room, help my Mom, and study English.

1) My brother is younger than my father.

=>My father is older than my brother.

2) Does your school have a library ?

=>Is there a libraby in your school?

3) My house is near the temple

=>My house isn't far from the temple.

4) Ba is the most intelligent in my class

=> No one in my class is more intelligent than Ba.

Từ a+b = ab = a:b\(\Rightarrow a=ab+b=b\left(a-1\right)\Rightarrow a\div b=a-1\left(b\ne0\right)\)

Theo đề bài thì a:b = a+b ; suy ra a-1=a+b\(\Rightarrow b=1\)

Thay b=1 vào a+b=a.b được a + 1 = a1\(\Rightarrow2a=1\Rightarrow a=\frac{1}{2}\)

Vậy \(a=\frac{1}{2}\)và b = 1

1.I'd like some chicken.

=> What would you like?

2.We smell the noodles at a store

=> Where do you smell the noodles?

3.I feel very tired

=> How do you feel?

4.My brother wants some orange juice.

=> What does your brother want?

5.There is some bread for dinner

=> What is there for dinner?

6.It's cool and nice in the fall in my country

=> How is the fall in your country?

7.Mary's going to play badminton with her sister

=> Who is Mary going to play badminton with?

8.Mr and Mrs.Smith come from Britain

=> Where do Mr and Mrs.Smith come from?

1842 = 2.3.13.19 = (2.19) .(3.13) = 38 . 39 

Vậy 2 số tự nhiên số la 38,39    

A. Choose the best answer

1. Nga often (drives/rides/goes) rides his bike to school.

2. Nhung is very good (with/for/at) at English anf History, but she (does/doesn't/don't) doesn't like Art much.

3. Would you like (to go/going/go) to go to the party?

4. The Vietnamese (decorate/celebrate/make) celebrate Tet at diffirent times each year.

5. This building is (tallest/taller/tall) taller than that building.

6. Lan is very pretty. She has chubby (legs/eyes/cheeks) cheeks.

7. Can you (passing/pass/to pass) pass me the biscuits? Yes, sure

8. Angel Falls is the highest (rock/valley/waterfall) waterfall in the world.

B. Fill in each blank with ONE suitable word:

1. Ha Long Bay is the nicest bay in Viet Nam.

2. The air in this area is polluted with smoke from factories.

3. A cinema is the place where we can watch a film.

4. Life in the countryside is boring because there aren't many things to do there.

5. Tan is very clever. He always has a lot of new ideas.

6. You have to take a boat to visit the castle because it's on a/an island.

7. You must take a rain coat to the Himalayas because it's cold and rainy there.