Từ điều kiện trên, ta có:

Trước hết, ta cần tìm Bội chung nhỏ nhất (BCNN) của 12, 15, và 18.

• Phân tích các số ra thừa số nguyên tố: $$12 = 2^2 \cdot 3$$ $$15 = 3 \cdot 5$$ $$18 = 2 \cdot 3^2$$

  BCNN(12, 15, 18) là tích của các thừa số nguyên tố chung và riêng, lấy với số mũ lớn nhất: $$BCNN(12, 15, 18) = 2^2 \cdot 3^2 \cdot 5 = 4 \cdot 9 \cdot 5 = 180$$

  Vì $(x - 8) \in BC(12, 15, 18)$, nên $(x - 8)$ phải là bội của 180. $$x - 8 = 180k \quad (k \in \mathbb{N}^*)$$(Vì $x$ nằm trong khoảng $500$ đến $700$, nên $x - 8$ phải là số dương, tức $k$ phải là số nguyên dương).

Ta có công thức:

Bây giờ, ta sử dụng điều kiện về khoảng của $x$:

• Trừ 8 vào cả ba vế: $$500 - 8 \le 180k \le 700 - 8$$ $$492 \le 180k \le 692$$
• Chia 180 cho cả ba vế: $$\frac{492}{180} \le k \le \frac{692}{180}$$ $$2.73... \le k \le 3.84...$$

Vì $k$ là số nguyên dương, giá trị duy nhất của $k$ thỏa mãn điều kiện là:

4. Kết luận

Thay $k = 3$ vào công thức của $x$:

Kiểm tra lại:

• Số sách $x = 548$.
• $500 \le 548 \le 700$ (Thỏa mãn).
• $548$ chia 12: $548 = 12 \cdot 45 + 8$ (dư 8).
• $548$ chia 15: $548 = 15 \cdot 36 + 8$ (dư 8).
• $548$ chia 18: $548 = 18 \cdot 30 + 8$ (dư 8).

Vậy, số sách trên kệ là 548 cuốn

• Hạt giống/Cây con: Tùy thuộc vào loại hoa bạn muốn trồng.
• Chậu trồng cây:
• • Chậu gieo hạt (khay ươm): Thường là khay nhựa có nhiều ô nhỏ, dùng để gieo hạt trước khi chuyển sang chậu lớn.
  • Chậu trồng chính: Có nhiều kích cỡ và chất liệu (nhựa, đất nung, sứ, xi măng...). Đảm bảo chậu có lỗ thoát nước.
• Đất trồng (Giá thể): Hỗn hợp chuyên dụng cho việc gieo hạt và trồng cây trong chậu.
• • Giá thể gieo hạt: Thường là hỗn hợp nhẹ, mịn, sạch (như Peat Moss, mụn dừa, trấu hun, hoặc đất tribat).
  • Đất trồng hoa: Hỗn hợp đất tơi xốp, giàu dinh dưỡng, thoát nước tốt (thường gồm đất thịt, phân hữu cơ, trấu hun/mụn dừa).
• Nước: Để tưới cho hạt và cây.

2. Dụng Cụ Làm Vườn Cơ Bản

• Bay làm vườn (xẻng nhỏ): Dùng để xúc đất, trộn đất, và di chuyển đất vào chậu.
• Cào mini (cào nhỏ): Dùng để làm tơi xốp bề mặt đất hoặc san phẳng đất trong chậu.
• Bình tưới:
• • Bình xịt/Phun sương: Rất quan trọng khi gieo hạt, giúp cung cấp độ ẩm nhẹ nhàng mà không làm trôi hạt giống.
  • Bình/vòi tưới có hoa sen: Dùng khi cây đã lớn hơn.
• Găng tay làm vườn: Bảo vệ tay khỏi đất và các chất bẩn.

3. Dụng Cụ Hỗ Trợ Khác

• Thẻ tên/Nhãn dán (Stake/Label): Dùng để ghi tên loại hạt, ngày gieo để dễ dàng theo dõi.
• Que chọc lỗ (hoặc ngón tay): Dùng để tạo lỗ nhỏ trên giá thể để đặt hạt giống vào.
• Sàng đất (nếu cần): Giúp làm mịn đất, loại bỏ các vật liệu thô lớn trước khi gieo hạt.
• Kéo cắt tỉa: Dùng để tỉa bớt lá hoặc cành khi cây lớn lên.
• Khay lót chậu: Đặt dưới chậu để hứng nước thừa, giữ vệ sinh khu vực trồng.
• Phân bón (dạng lỏng hoặc hạt): Cung cấp dinh dưỡng cho cây khi cây đã nảy mầm và phát triển. ok nha

motagem rugada

tui thấy nhạc midu moutain với motagem tropica nada hay nhất á nghe hay v :>

quả bóng chứ sao

helpppp

Mark the letter A, B, C, or D to indicate the word whose underlined part is pronounced differently from that of the rest in each of the following questions.

Question 1. A. thought           B. although          C. thanks             D. think

Question 2. A. now                 B. cold                 C. know              D. boat

Choose the word which has a different stress pattern from the others.

Question 3. A. landmark         B. helmet              C. machine          D. palace

Question 4. A. channel           B. repair               C. water              D. bookshelf

Mark the letter A, B, C, or D to indicate the correct answer to each of the following questions.

Question 5. I _________ aerobics three times a week at my local gym.

    A. play                   B. take                   C. do                      D. go

Question 6. My mum bought me a pair of _________ for my swimming class.

    A. sport shoes        B. rackets               C. skateboards        D. goggles

Question 7. What _________ when you come to see me next month?

    A. wont you do      B. will you do        C. will you does     D. will did you

Question 8. I _________ the sun today because it was cloudy.

    A. not see               B. am not seeing     C. don’t see            D. didn’t see

Question 9. A/ An _________ can help us to keep food fresh.

    A. smart clock        B. fridge                 C. washing machine             D. electric cooker

Question 10. _________ did you go last night? – I just stayed at home.

    A. How                  B. Where                C. When                 D. Who

Question 11. “_________ is your favourite football players?” – “I am not into football.”

    A. Which               B. Whom               C. What                 D. Who

Question 12. It was really hot in Ha Noi this summer _________ it's normally cool there.

    A. and                    B. so                      C. although            D. because

Question 13. “When will we have flying cars?” - “_________.”

    A. I don’t cycle often.                           B. I don’t think much about it.

    C. As soon as possible.                         D. Maybe sooner than you think.

Question 14. She had a headache, _________ she decided to stay at home.

    A. but                    B. or                      C. because              D. so

Question 15. I have a bag. _________ bag is over there.

    A. A                       B. These                 C. The                    D. An

Question 16. I didn’t have my textbook for English class, so Anna lent me_________.

    A. your                  B. their                   C. mine                  D. hers

Question 17. In the future, robots _________ behave like humans.

    A. need                  B. must                  C. should               D. might

READING

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct option that best fits each numbered blank.

Three ways everyone can help make the Earth a greener place is to reduce, reuse, and recycle!

When people reduce it means they are using (18)________ of something. This allows us to create less waste. Turning off the faucet when we brush our teeth is a simple way to reduce. This is a small action that prevents us from wasting (19)________.

Another small action people can take is to reuse things we already have. Taking bags to the store (20)________ we shop for food is one way to reuse them. Using both sides of piece of paper before getting a new one is another way to reuse.

(21)________ is when new materials are created from old ones. Paper, plastic, and metal are all materials that can be recycled. Things like newspapers, soda cans, and plastic bags can all be turned (22)________ new objects if we take the time to recycle them!

Question 18. A. less                B. more                C. much               D. little

Question 19. A. time               B. electricity        C. water              D. energy

Question 20. A. how               B. what                C. when               D. why

Question 21. A. Repeat          B. Reducing         C. Reusing           D. Recycling

Question 22. A. out                B. up                    C. down              D. into

Read the text and then choose the best answer A, B, C, or D.

In the future, we will live in amazing new houses. Our houses will use the sun or the wind to make electricity. We won’t use cookers, dishwashers or washing machines because robots will help us. We will have robots to cook our dinner and wash our clothes. We will have robots to look after our children. We won’t use computers. We will have special remote control units. We can surf the internet, send and receive emails and order food from the markets without getting out of bed.

We won’t have TVs or CD players because we will have watches that play music, take pictures and tell the time. Our cars won’t use gas. They will use energy from air, water and plants. In the future the air won’t be polluted. Our world will be a great place to live in.

Question 23. Our house will use _______ to make electricity.

    A. solar and wind energy                      B. nuclear energy

    C. wind energy                                     D. solar energy

Question 24. Robots won’t help us to _______.

    A. surf the internet                               B. wash our clothes

    C. cook our dinner                               D. look after our children

Question 25. We will have special remote control units to _______.

    A. send and receive emails                    B. all answers are correct

    C. surf the internet                               D. order food from the markets

Question 26. Our watches won’t _______.

    A. play music         B. tell the time        C. make electricity                D. take pictures

Question 27. Cars won’t use energy from _______.

    A. water                 B. wind                  C. plants                              D. air

WRITING

Mark the letter A, B, C or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Question 28. Many people are concerned that the popular of online learning will reduce the role of teachers.

    A. Many                B. popular              C. will reduce         D. of

Question 29. Scientist are working hard to discover new sources of energy.

    A. Scientist            B. working             C. to discover         D. energy

Mark the letter A, B, C or D on your answer sheet to indicate the sentence that is made from the given cues in each of the following questions.

Question 30. I/ want/ save the environment/ I/ use/ recycled items.

    A. I want to save the environment, or I use recycled items.

    B. I want to save the environment, because I use recycled items.

    C. I want to save the environment, so I use recycled items.

    D. I want to save the environment, and I use recycled items.

Question 31. My students/ come/ complete/ project/ tomorrow

    A. My students will to come here to complete this project tomorrow.

    B. My students might coming here to complete this project tomorrow.

    C. My students might come here to complete this project tomorrow.

    D. My students come here to complete this project tomorrow.

Question 32. What/ colourful/ nice/ picture!

    A. What a colourful and nice picture!

    B. What colourful and nice picture!

    C. What colourful and nice picture is!

    D. What is a colourful and nice picture!

help toan bang khó quá

Mark the letter A, B, C, or D to indicate the word whose underlined part is pronounced differently from that of the rest in each of the following questions.

Question 1. A. thought           B. although          C. thanks             D. think

Question 2. A. now                 B. cold                 C. know              D. boat

Choose the word which has a different stress pattern from the others.

Question 3. A. landmark         B. helmet              C. machine          D. palace

Question 4. A. channel           B. repair               C. water              D. bookshelf

Mark the letter A, B, C, or D to indicate the correct answer to each of the following questions.

Question 5. I _________ aerobics three times a week at my local gym.

    A. play                   B. take                   C. do                      D. go

Question 6. My mum bought me a pair of _________ for my swimming class.

    A. sport shoes        B. rackets               C. skateboards        D. goggles

Question 7. What _________ when you come to see me next month?

    A. wont you do      B. will you do        C. will you does     D. will did you

Question 8. I _________ the sun today because it was cloudy.

    A. not see               B. am not seeing     C. don’t see            D. didn’t see

Question 9. A/ An _________ can help us to keep food fresh.

    A. smart clock        B. fridge                 C. washing machine             D. electric cooker

Question 10. _________ did you go last night? – I just stayed at home.

    A. How                  B. Where                C. When                 D. Who

Question 11. “_________ is your favourite football players?” – “I am not into football.”

    A. Which               B. Whom               C. What                 D. Who

Question 12. It was really hot in Ha Noi this summer _________ it's normally cool there.

    A. and                    B. so                      C. although            D. because

Question 13. “When will we have flying cars?” - “_________.”

    A. I don’t cycle often.                           B. I don’t think much about it.

    C. As soon as possible.                         D. Maybe sooner than you think.

Question 14. She had a headache, _________ she decided to stay at home.

    A. but                    B. or                      C. because              D. so

Question 15. I have a bag. _________ bag is over there.

    A. A                       B. These                 C. The                    D. An

Question 16. I didn’t have my textbook for English class, so Anna lent me_________.

    A. your                  B. their                   C. mine                  D. hers

Question 17. In the future, robots _________ behave like humans.

    A. need                  B. must                  C. should               D. might

READING

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct option that best fits each numbered blank.

Three ways everyone can help make the Earth a greener place is to reduce, reuse, and recycle!

When people reduce it means they are using (18)________ of something. This allows us to create less waste. Turning off the faucet when we brush our teeth is a simple way to reduce. This is a small action that prevents us from wasting (19)________.

Another small action people can take is to reuse things we already have. Taking bags to the store (20)________ we shop for food is one way to reuse them. Using both sides of piece of paper before getting a new one is another way to reuse.

(21)________ is when new materials are created from old ones. Paper, plastic, and metal are all materials that can be recycled. Things like newspapers, soda cans, and plastic bags can all be turned (22)________ new objects if we take the time to recycle them!

Question 18. A. less                B. more                C. much               D. little

Question 19. A. time               B. electricity        C. water              D. energy

Question 20. A. how               B. what                C. when               D. why

Question 21. A. Repeat          B. Reducing         C. Reusing           D. Recycling

Question 22. A. out                B. up                    C. down              D. into

Read the text and then choose the best answer A, B, C, or D.

In the future, we will live in amazing new houses. Our houses will use the sun or the wind to make electricity. We won’t use cookers, dishwashers or washing machines because robots will help us. We will have robots to cook our dinner and wash our clothes. We will have robots to look after our children. We won’t use computers. We will have special remote control units. We can surf the internet, send and receive emails and order food from the markets without getting out of bed.

We won’t have TVs or CD players because we will have watches that play music, take pictures and tell the time. Our cars won’t use gas. They will use energy from air, water and plants. In the future the air won’t be polluted. Our world will be a great place to live in.

Question 23. Our house will use _______ to make electricity.

    A. solar and wind energy                      B. nuclear energy

    C. wind energy                                     D. solar energy

Question 24. Robots won’t help us to _______.

    A. surf the internet                               B. wash our clothes

    C. cook our dinner                               D. look after our children

Question 25. We will have special remote control units to _______.

    A. send and receive emails                    B. all answers are correct

    C. surf the internet                               D. order food from the markets

Question 26. Our watches won’t _______.

    A. play music         B. tell the time        C. make electricity                D. take pictures

Question 27. Cars won’t use energy from _______.

    A. water                 B. wind                  C. plants                              D. air

WRITING

Mark the letter A, B, C or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Question 28. Many people are concerned that the popular of online learning will reduce the role of teachers.

    A. Many                B. popular              C. will reduce         D. of

Question 29. Scientist are working hard to discover new sources of energy.

    A. Scientist            B. working             C. to discover         D. energy

Mark the letter A, B, C or D on your answer sheet to indicate the sentence that is made from the given cues in each of the following questions.

Question 30. I/ want/ save the environment/ I/ use/ recycled items.

    A. I want to save the environment, or I use recycled items.

    B. I want to save the environment, because I use recycled items.

    C. I want to save the environment, so I use recycled items.

    D. I want to save the environment, and I use recycled items.

Question 31. My students/ come/ complete/ project/ tomorrow

    A. My students will to come here to complete this project tomorrow.

    B. My students might coming here to complete this project tomorrow.

    C. My students might come here to complete this project tomorrow.

    D. My students come here to complete this project tomorrow.

Question 32. What/ colourful/ nice/ picture!

    A. What a colourful and nice picture!

    B. What colourful and nice picture!

    C. What colourful and nice picture is!

    D. What is a colourful and nice picture!

cứu tui ôg giúp đc ko

Mark the letter A, B, C, or D to indicate the correct answer to each of the following questions.

Question 5. I _________ aerobics three times a week at my local gym.

    A. play                   B. take                   C. do                      D. go

Question 6. My mum bought me a pair of _________ for my swimming class.

    A. sport shoes        B. rackets               C. skateboards        D. goggles

Question 7. What _________ when you come to see me next month?

    A. wont you do      B. will you do        C. will you does     D. will did you

Question 8. I _________ the sun today because it was cloudy.

    A. not see               B. am not seeing     C. don’t see            D. didn’t see

Question 9. A/ An _________ can help us to keep food fresh.

    A. smart clock        B. fridge                 C. washing machine             D. electric cooker

Question 10. _________ did you go last night? – I just stayed at home.

    A. How                  B. Where                C. When                 D. Who

Question 11. “_________ is your favourite football players?” – “I am not into football.”

    A. Which               B. Whom               C. What                 D. Who

Question 12. It was really hot in Ha Noi this summer _________ it's normally cool there.

    A. and                    B. so                      C. although            D. because

Question 13. “When will we have flying cars?” - “_________.”

    A. I don’t cycle often.                           B. I don’t think much about it.

    C. As soon as possible.                         D. Maybe sooner than you think.

Question 14. She had a headache, _________ she decided to stay at home.

    A. but                    B. or                      C. because              D. so

Question 15. I have a bag. _________ bag is over there.

    A. A                       B. These                 C. The                    D. An

Question 16. I didn’t have my textbook for English class, so Anna lent me_________.

    A. your                  B. their                   C. mine                  D. hers

Question 17. In the future, robots _________ behave like humans.

    A. need                  B. must                  C. should               D. might

READING

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct option that best fits each numbered blank.

Three ways everyone can help make the Earth a greener place is to reduce, reuse, and recycle!

When people reduce it means they are using (18)________ of something. This allows us to create less waste. Turning off the faucet when we brush our teeth is a simple way to reduce. This is a small action that prevents us from wasting (19)________.

Another small action people can take is to reuse things we already have. Taking bags to the store (20)________ we shop for food is one way to reuse them. Using both sides of piece of paper before getting a new one is another way to reuse.

(21)________ is when new materials are created from old ones. Paper, plastic, and metal are all materials that can be recycled. Things like newspapers, soda cans, and plastic bags can all be turned (22)________ new objects if we take the time to recycle them!

Question 18. A. less                B. more                C. much               D. little

Question 19. A. time               B. electricity        C. water              D. energy

Question 20. A. how               B. what                C. when               D. why

Question 21. A. Repeat          B. Reducing         C. Reusing           D. Recycling

Question 22. A. out                B. up                    C. down              D. into

Read the text and then choose the best answer A, B, C, or D.

In the future, we will live in amazing new houses. Our houses will use the sun or the wind to make electricity. We won’t use cookers, dishwashers or washing machines because robots will help us. We will have robots to cook our dinner and wash our clothes. We will have robots to look after our children. We won’t use computers. We will have special remote control units. We can surf the internet, send and receive emails and order food from the markets without getting out of bed.

We won’t have TVs or CD players because we will have watches that play music, take pictures and tell the time. Our cars won’t use gas. They will use energy from air, water and plants. In the future the air won’t be polluted. Our world will be a great place to live in.

Question 23. Our house will use _______ to make electricity.

    A. solar and wind energy                      B. nuclear energy

    C. wind energy                                     D. solar energy

Question 24. Robots won’t help us to _______.

    A. surf the internet                               B. wash our clothes

    C. cook our dinner                               D. look after our children

Question 25. We will have special remote control units to _______.

    A. send and receive emails                    B. all answers are correct

    C. surf the internet                               D. order food from the markets

Question 26. Our watches won’t _______.

    A. play music         B. tell the time        C. make electricity                D. take pictures

Question 27. Cars won’t use energy from _______.

    A. water                 B. wind                  C. plants                              D. air

WRITING

Mark the letter A, B, C or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Question 28. Many people are concerned that the popular of online learning will reduce the role of teachers.

    A. Many                B. popular              C. will reduce         D. of

Question 29. Scientist are working hard to discover new sources of energy.

    A. Scientist            B. working             C. to discover         D. energy

Mark the letter A, B, C or D on your answer sheet to indicate the sentence that is made from the given cues in each of the following questions.

Question 30. I/ want/ save the environment/ I/ use/ recycled items.

    A. I want to save the environment, or I use recycled items.

    B. I want to save the environment, because I use recycled items.

    C. I want to save the environment, so I use recycled items.

    D. I want to save the environment, and I use recycled items.

Question 31. My students/ come/ complete/ project/ tomorrow

    A. My students will to come here to complete this project tomorrow.

    B. My students might coming here to complete this project tomorrow.

    C. My students might come here to complete this project tomorrow.

    D. My students come here to complete this project tomorrow.

Question 32. What/ colourful/ nice/ picture!

    A. What a colourful and nice picture!

    B. What colourful and nice picture!

    C. What colourful and nice picture is!

    D. What is a colourful and nice picture!

đào không thuộc m cóc thuộc m dưa hấu thuộc m

tui có yeti trade sang trái j xịn xịn theanh

mới randum ra hôm qua yeti