Một vật khối lượng 2kg được kéo bởi một lực F hướng lên hợp với phương ngang một góc alpha = 30 độ. Lực F có độ lớn 8N. Biết sau khi bắt đầu chuyển động 2s từ trạng thái đứng yên vật đi được quãng đường 4m. Lấy g = 10m/s2. a. Tính hệ số ma sát giữa vật và mặt ngang. b. Để cho vật có thể chuyển động thẳng đều thì F có độ lớn là bao nhiêu?

Tính: $\frac{5}{4.6}$ +$\frac{5}{6.8}$ + $\frac{5}{8.10}$ +........+ $\frac{5}{298.300}$ Các bạn giải hộ mình nha! Giải chi tiết dùm mình! Mình cảm ơn trc😊

VI. Rewrite the following questions in reported speech, using question words before to-infinitives. 1. “What should we do to help her overcome stress?” They didn’t know 2. “Should I discuss this matter with my teammates?” Jonas wondered 3. “Where should I register for a course on life skills?” An asked Mary 4. “How should we find a support center for the homeless?” James and Lily couldn’t tell 5. “When should we start our campaign?” They had no idea 6. “Mom, who should I call upon arriving at the airport?” Trang asked her mother 7. “Should I dial 18001567 to ask for advice about family problems?" Phong was not sure 8. “What should we do to help those disadvantaged children?” They wondered 9. “When should I start teaching my children to cook?” She couldn’t decide 10. “How should I deal with negative emotions and stress?” Hoa asked Nam VII. Fill in each blank with a suitable preposition. 1. He felt that they were making fun him, though he could not understand why. 2. He wasn’t able to cope the stresses and strains of the job. 3. We have to improve and increase mass participation sports. 4. This goes beyond the boundaries what is accepted. 5. My parents never put any pressure me to get a job. 6. You can dial 114 in case of fire dealing area codes. 7. She gave up German in order to concentrate her French. 8. Parents need to continue to empathize the child.

Muốn kéo một vật có trọng lượng P = 1000N chuyển động đều lên một mặt phẳng nghiêng góc 60 độ so với đường thẳng đứng, người ta phải dùng một lực F có phương song song với mặt phẳng nghiêng và có độ lớn 600N. Hỏi vật sẽ chuyển động xuống mặt phẳng nghiêng với gia tốc bao nhiêu khi không có lực F. Biết giữa vật và mặt phẳng nghiêng có ma sát. Lấy g = 10m/s2.

Sự khác nhau giữa Bridge và Gap

IV. Complete the sentences with suitable question words. 1. He doesn’t know to ask for advice about this situation. 2. Be sure to eat when you arrive in Vietnam. 3. They are going to tell me to do to survive in a storm. 4. I asked Jane to show me to deal with bullying at school. 5. He wondered to start revising for the final exam. 6. The rules didn’t specify to speak to in case of an emergency. 7. You need to find out to overcome stress and worry. 8. I don’t know to turn for help. 9. I had no idea to write my home paper about. 10. Tell me to press the button. V. Rewrite the following sentences using question words before to-infinitives. 1. I don’t know where I should visit this summer vacation. 2. Could you tell me who I should ask for advice? 3. She wondered what she should write in the final essay. 4. I have no idea who I should contact in case of emergency. 5. They can’t decide when they leave for America. 6. I’m not sure what I should cook for my son’s birthday party. 7. Could you tell me where I should put my umbrella? 8. He asked himself what he should send her as a present. 9. I have no idea when I should leave for Japan. 10. She wondered how she should resolve the conflict.

Chứng minh rằng: $a, P_{n}= (n-1)P_{n-1} + (n-2)P_{n-2} +...+2P_{2} + P_{1} +1$ $b, 1 + \dfrac{1}{1!} + \dfrac{1}{2!} + \dfrac{1}{3!} +...+ \dfrac{1}{n!} < 3$ $c, \dfrac{n^{2}}{n!} = \dfrac{1}{(n-1)!} + \dfrac{1}{(n-2)!}$

ko cần làm bài 6 ạ, khỏi giải thích. Nhanh là được

Giúp e vs mn ơi! Cần giải thích nx nha! Vote 5*

I. Complete the sentences with the words from the box. There are two words that you do not need to use. 1. He gets when people don’t understand what he’s trying to say. 2. I’m not about her - she can take care of herself. 3. She was very as she waited for the interview. 4. The teacher wants the children to feel about asking questions when they don’t understand. 5. Anna got 10 marks for her English test. She felt absolutely about that result. 6. She’s terribly about losing her job. 7. He told himself to stay whenever he was put into a harsh situation. 8. As soon as I had made the final decision, I felt a lot more . II. Turn the following sentences into reported speech. 1. “Our daughter wants to study abroad for a year,” they said. 2. “Have you ever experienced school pressures?” she asked me. 3. “Yesterday I couldn’t watch my favourite cartoon on Disney Channel,” he said. 4. “Is the weather good in Shanghai in the summer?” Jane asked me. 5. “What are the skills that you find the most difficult to learn?” she asked me. 6. “Would you bring me a cup of coffee, please?” she told me. 7. “I’ll come and help you on Saturday,” Joana told me. 8. “When will you come back home?” my mom asked me. 9. “Did you need any help on this assignment?” the teacher asked me. 10. “My friend got engaged to a German last month,” Danny told Ann. III. Complete the sentences with correct tense of verbs. 1. The interviewer asked me what I (can) do if I were offered the job. 2. Mandy asked me if the boys (read) the book at present. 3. The manager told me that I (travel) from place to place the following month. 4. They said they (never/ be) to Scotland until last year. 5. Jason and Victoria told me they (do) their best in the exams the following day. 6. I wondered why Nick (not go) to New York the summer before. 7. John told me that there (may) not be dessert after dinner. 8. She asked me if everyone (must) contact the Magic Number in emergency situations. 9. My mom said she (be) going to visit a friend of hers in London. 10. Shannon said that she (need) to take care of her baby.