Cho ba tập hợp:
F={x∈R∣∣f(x)=0}; G={x∈R∣∣g(x)=0}; H={x∈R∣∣f(x)+g(x)=0}.
Mệnh đề nào sau đây là đúng?
Câu hỏi liên quan
Một người đứng ở một vách đá nhô ra biển và ném một hòn đá theo phương ngang xuống biển với tốc độ 16 m/s. Vách đá cao 70 m so với mặt nước biển. Lấy g = 9,8 m/s2. Sau bao lâu thì hòn đá chạm vào mặt nước?
Read the following passage about The Longitude Prize and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions
On a stormy night in 1707, four ships struck rocks off the south coast of England and sank. [I] One thousand, four hundred sailors were drowned. [II] The ships had crashed because they had no way of knowing how far they had travelled in a particular direction; they could not calculate their longitude, which required accurate time measurement. [III] In such difficult circumstances, they believed that the best response to the disaster was a competition: the Longitude Prize. [IV]
The Longitude Prize was no ordinary competition. To win it, someone had to find a way of calculating how far a ship had travelled east or west from its point of departure. Geniuses such as Sir Isaac Newton had failed to find a solution, so to ensure the interest of Britain’s greatest scientific minds, the government offered a prize of £20,000 — the equivalent of £2.6 million in today’s money. But to everyone’s surprise, it wasn’t a famous academic who solved the problem, but an unknown carpenter.
When John Harrison wasn’t working with wood, he was making clocks. An accurate clock would allow sailors to calculate their position, but at the time it was thought impossible to create a mechanical clock that could work on a ship. The movement of the sea and the changes in temperature destroyed the delicate parts. However, after three frustrated attempts, Harrison’s fourth sea clock, H4, finally triumphed. Its mechanics were so good that the H4 worked better than most clocks on land.
The Longitude Prize and Harrison’s success generated a lot of interest in the 18th century, but it was soon forgotten. However, in 2013, the British government created a new Longitude Prize, offering £10 million to the person who could solve a great challenge to humanity. An enthralled public then took part in a TV programme where viewers chose one challenge from a list of six for scientists to focus on. The question now is, will someone be able to solve it just as well as Harrison solved the challenge presented to him?
Which of the following is TRUE according to the passage?
Cho biết giá trị của \(T = {\cos ^4}x\;(2{\cos ^2}x - 3) + {\sin ^4}x\;(2{\sin ^2}x - 3)\) là?
Có bao nhiêu loại phần mềm đồ họa?
Tính chất nền kinh tế Việt Nam có sự biến đổi như thế nào sau khai thác thuộc địa lần thứ nhất?
Đâu là đặc điểm nổi bật của ngành nông nghiệp ở Nhật Bản?
Hệ quy chiếu bao gồm:
Năm 1903, hai anh em nhà Rai (Mỹ) đã thử nghiệm thành công loại phương tiện nào sau đây?
Chiến thắng nào của quân dân nhà Trần đánh dấu thất bại đau đớn nhất của quân Mông – Nguyên trong lần thứ ba xâm lược?
Điểm khác biệt của Nhật Bản so với Việt Nam giữa thế kỉ XIX là:
Câu tục ngữ nào dưới đây có nội dung nói về đặc điểm của cơ chế thị trường?
Read the passage carefully
1. Do you find yourself yawning all day at school? You probably need more sleep. However, it is not just how much sleep you get that is important. What you do before bedtime also has a huge effect on how you feel the next day. If you spend time chatting to someone on social media, or reading a book on your e- reader, you are not alone.
2. All devices' screens give out a large amount of blue light, which affects the body's production of the sleep hormone, melatonin, which can change your sleep patterns. So it is not just getting to sleep that becomes hard, but the quality of your sleep also suffers. The result is that you can wake up several times during the night, and have difficulty getting up in the morning.
3. Sleep is food for the brain, so not sleeping well can be a severe problem for anyone, especially for teenagers, because their brains are still developing. When you do not sleep well, it can be difficult to concentrate at school, which makes it harder to learn and get good grades. It can also affect your mood, making you feel sad or anxious.
4. So, it is clear you should not use your phone before you go to sleep. Why not leave it in another room? Nothing on social media is so important that it cannot wait a few hours! You should rediscover paper books and enjoy feeling tired and sleepy before bedtime rather than wondering why your best friend has not liked your photo! How will you wake up? You do not have to use the alarm on your phone. Go and buy yourself an old-fashioned alarm clock! The negative effects that screen time is having on sleep have been in the news a lot recently, so manufacturers of smartphones and tablets have added a feature to the mobile devices that can help reduce these. Most new phones have a night-time setting that changes the colour of the screen so that it gives out less blue light. If you really cannot avoid going onto social media at bedtime, think about turning on this setting on your phone.
(Adapted from Prepare)
Which of the following can be affected by blue light from digital screens?
Read the following advertisement and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 1 to 6.
Glow Up with Radiance – Your Beauty, Your Power!
Looking for the secret to flawless skin? Introducing GlowUp, the ultimate cosmetic brand that enhances your natural beauty with the finest ingredients. Our products are designed to keep your skin (1) ______ all day long, giving you a fresh and radiant look.
Each item in our collection is crafted with (2) ______, ensuring the best results. Our innovative serums, known to bring out your inner glow, work deep (3) ______ your skin for a lasting effect.
With GlowUp, you never have to worry about harsh chemicals. Our products are made by organic extracts, (4) ______ your skin healthy and nourished. Say goodbye to dull skin and hello to a glowing complexion!
Join thousands of happy customers who trust GlowUp to (5) ______ their beauty routine effortlessly. Don’t wait – it’s time (6) ______ yourself with the best skincare on the market!
Read the passage carefully. Choose an option (A, B, C or D) that best answers each question from 23 to 30.
1. How do children learn about wildlife? And is what they learn the sort of thing they should be learning? It is my belief that children should not just be acquiring knowledge of animals but also developing attitudes and feelings towards them based on exposure to the real lives of animals in their natural habitats. But is this happening?
2. Some research in this area indicates that it is not. Learning about animals in school is often completely disconnected from the real lives of real animals, with the result that children often end up with little or no understanding or lasting knowledge of them. They learn factual information about animals, aimed at enabling them to identify them and have various abstract ideas about them, but that is the extent of their learning. Children's storybooks tend to personify animals as characters rather than teach about them.
3. For direct contact with wild and international animals, the only opportunity most children have is visiting a zoo. The educational benefit of this for children is often given as the main reason for doing it but research has shown that zoo visits seldom add to children's knowledge of animals – the animals are simply like exhibits in a museum that the children look at without engaging with them as living creatures. Children who belong to wildlife or environmental organizations or who watch wildlife TV programmes, however, show significantly higher knowledge than any other group of children studied in research. The studies show that if children learn about animals in their natural habitats, particularly through wildlife-based activities, they know more about them than they do as a result of visiting zoos or learning about them in the classroom.
4. Research has also been done into the attitudes of children towards animals. It shows that in general terms, children form strong attachments to individual animals, usually their pets, but do not have strong feelings for animals in general. This attitude is the norm regardless of the amount or kind of learning about animals they have at school. However, those children who watch television wildlife programs show an interest in and affection for wildlife in its natural environment, and their regard for animals in general is higher.
Which of the following is NOT true according to the passage?
Một vật được thả rơi tự do. Lấy gia tốc rơi tự do là 9,8 m/s2. Hỏi trong giây thứ ba kể từ lúc được thả rơi thì vận tốc của vật đã tăng lên bao nhiêu?
Nguyên tử R có tổng số proton, neutron và electron là 95, trong đó số hạt mang điện nhiều hơn số hạt không mang điện là 25. Ion X2+ có số hạt electron là
Choose A, B, C or D that has the CLOSEST meaning to the given sentence in each question.
The company's profits were so high that they decided to give everyone a bonus.
Phân lớp d có thể chứa số electron tối đa là
Hệ quả nào sau đây không phải là của khu vực hóa kinh tế?