Cây đậu Hà Lan khi trồng có chiều cao \(3\) centimet. Gọi \(h\left( t \right)\) là độ cao tính bằng centimet của cây đậu Hà Lan tại thời điểm \(t\) kể từ khi được trồng, với \(t\) tính theo tuần. Khảo sát cho thấy tốc độ tăng chiều cao của cây đậu Hà Lan sau khi trồng là $h^{\text{'}}\left(t\right)=-0,02t^3+0,3t^2$ (centimet/tuần).

Biết điện thế tại điểm M trong điện trường là 40V. Electron có điện tích e = -1,6.10^-19 C đặt tại điểm M có thế năng là:

Năm 1920, Nguyễn Ái Quốc có hoạt động nào sau đây?

Trong ngôn ngữ Python, tên nào sau đây đặt sai theo quy tắc?

Một xilanh đang chứa một khối khí, khi đó pít - tông cách đáy xilanh một khoảng 15cm. Hỏi phải đẩy pít – tông theo chiều nào, một đoạn bằng bao nhiêu để áp suất khí trong xilanh tăng gấp 3 lần? Coi nhiệt độ của khí không đổi trong quá trình trên.

Muốn kết nối với Internet phải sử dụng các dịch vụ của nhà cung cấp dịch vụ kết nối. Đâu không phải là nhà cung cấp dịch vụ Internet:

Read the passage carefully. Choose an option (A, B, C, or D) that best answers each question from to 646 to 650:

1. Millions of people are using cellphones today. In many places, it is actually considered unusual not to use one. In many countries, cellphones are very popular with young people. They find that the phones are more than a means of communication - having a mobile phone shows that they are cool and connected.

2. The explosion in mobile phone use around the world has made some health professionals worried. Some doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.

3. On the other hand, medical studies have shown changes in the brain cells of some people who use mobile phones. Signs of change in the tissues of the brain and head can be detected with modern scanning equipment. In one case, a traveling salesman had to retire at young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't  agree.

4. What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.

5. As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often.

According to the passage, what can be inferred about cellphones?

Bước sóng ánh sáng có hiệu quả cao nhất đối với quang hợp là gì?

Xác định ý đúng: Đặc điểm nào không đúng với vai trò của nội thương?

Read the following passage about Renewable energy sources and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

          [I] Renewable energy sources, such as solar, wind, and hydroelectric power, have gained global popularity as a sustainable alternative to fossil fuels. [II] Unlike coal and oil, renewable energy generates electricity without releasing harmful emissions, making it a cleaner option for the environment (Jacobson et al., 2017). [III] However, despite the advantages of renewable energy, there are still notable challenges that need to be addressed for it to fully replace traditional energy sources (Ell Abban et al., 2014). [IV]

          One major advantage of renewable energy is its sustainability. Renewable resources, unlike fossil fuels, are naturally replenished and do not deplete over time. For instance, solar power harnesses energy from sunlight, which is virtually endless. In addition, renewable energy contributes to reducing greenhouse gas emissions, which helps combat climate change. Many countries are increasingly investing in renewable technologies to decrease their carbon footprint and meet international climate goals.

          However, renewable energy has certain limitations. One significant issue is its intermittent nature; for example, solar and wind power depend on weather conditions, making it difficult to generate a consistent power supply. This variability can disrupt the energy grid, which relies on a steady supply of electricity to meet demand. Another challenge is the high initial cost of setting up renewable energy facilities. Although prices have decreased in recent years, installing solar panels or wind turbines still requires substantial upfront investment (IRENA, 2019).

          Despite these challenges, advancements in technology are gradually making renewable energy more efficient and accessible. Improved energy storage systems, such as batteries, allow excess power generated during favourable conditions to be stored and used later, ensuring a more reliable energy supply. As technology and infrastructure improve, renewable energy may eventually.

Which of the following can be inferred from the passage?

Chủ thể nhà nước có vai trò gì khi tham gia vào hoạt động kinh tế?

Cho hàm số \(f(x) = \frac{{ax + b}}{{cx + d}}\) \(({\rm{a}},{\rm{b}},{\rm{c}},{\rm{d}} \in \mathbb{R},{\rm{ac}} \ne 0)\) có đồ thị như hình bên. Đường tiệm cận đứng của đồ thị hàm số là

Trong thực tế, IoT có thể ứng dụng trong lĩnh vực gì?

Em là chủ thể tiêu dùng khi