cho a,b,c >0 và abc=1. CMR : 1/a^2(b+c) + 1/b^2(a+c) + 1/c^2(b+a) >= 3/2

mọi người giải hộ em câu 2b với ạ. Xem hộ em sai chỗ nào với ạ? Em cảm ơn

Một thang máy có khối lượng 1 tấn có thể chịu tối đa 800 kg khi chuyển động thang máy còn chịu lực cản không đổi 4.10^-3 N để đưa thang máy lên cao với v=3m/s thì công suốt động cơ bằng bao nhiêu cho g=9.8m/s^2

III. READING Choose the word or phrase (a, b, c or d) that best fits the blank space in the following passage. When I was a boy, children always objected to (36) _______ school uniform but teachers were (37)_______ on it because they said all of us looked alike. Otherwise, they said, children would compete with (38) and the poor children would be unhappy because people would see straight away (39)_______ poor they were. In recent years, however, many schools have give up the idea of making children wear uniform, but, fairly enough, now that children can wear (40)_______ they like, they have adopted a uniform of their own. When some journalists visited a London school they found that all the boys and girls were dressed (41)_______ jeans. One girl said she would rather die than wear a coat instead of a jersey because (42)_______ wants to look different from the other children in the class. Parents may not be as happy about this as children, but they (43)_______ to be, because this new kind of uniform is one that children like, not something they have been (44)_______ to wear, and it is also (45)_______ cheaper than school uniforms used to be. 36. a. taking b. dressing c. wearing d. putting 37. a. carried b. keen c. gone d. keep 38. a. together b. another c. others d. each other 39. a. how b. which c. what d. however 40. a. like b. such as c. as d. as if 41. a. on b. in c. by d. with 42. a. everyone b. anyone c. someone d. no one 43. a. ought b. should c. must d. might 44. a. taken b. employed c. forced d. pushed 45. a. much b. more c. too d. very Read the passage below carefully and choose the correct answer a, b, c or d. In most animals, dental decay is a rare problem. In man, and especially in the rich West, the disease has reached epidemic proportions. The cause of tooth decay in human beings is a bacterium that feeds on the sugar in our food. It digests the sugar more easily by converting it into an acid. The acid then dissolves the enamel, the outer coating of the teeth, and finally attacks the living nerve within. The result is the extreme pain we know as toothache. • epidemic proportions (n): nạn dịch • digest (v): tiêu hóa • convert (sth into sth) (v): chuyển hoá (...thành...) 46. According to the passage, animals ______. a. never suffer from tooth decay b. seldom suffer from tooth decay c. suffer from tooth decay as much as people do d. suffer from tooth decay more commonly than people do 47. The problem of tooth decay in the rich Western countries ________. a. is decreasing each year b. has already been controlled c. has been increasing slowly d. is now almost out of control 48. Human teeth decay when they are attacked by a kind of _______. a. sugar b. acid d. food 49. Decay cannot begin until the bacterium produces _______. a. food from sugar b. sugar from food c. acid from sugar d. sugar from acid 50. The term "tooth decay” refers to the ________. a. digestion of the food b. conversion of the sugar c. production of the acid d. dissolution of the enamel

tìm n ∈ Z c) (n ² - 5n) ∈ B(n - 2 ) d) (6n - 4) ∈ B(1-2n) e) n+1 ∈ Ư(n ²+2n-3) mai mk nộp rùi

TEST 11 I. PHONETICS Choose the word whose underlined part pronounced differently from that of the others. 1. a. chopstick b. challenge c. champagne d. charity 2. a. seat b. head c. meat d. feed 3. a. watches b. washes c. rises d. lives Choose the word whose main stress pattern is not the same as that of the others. 4. a. climate b. campus c. control d. capture 5. a. exhibition b. precaution c. position d. selection II. GRAMMAR AND VOCABULARY Choose the word or phrase (a, b, c or d) that best fits the blank space in each sentence. 6. Thanks _______ our English teacher, we have learned many English songs. a. to b. for c. on d. Ø 7. The floor was covered _______ a litter _______ newspapers, clothes and empty cups. a. with - of b. of - with c. on - of d. in - of 8. I am fed _______ hanging around here with nothing to do. a. up on b. out of c. up with d. by 9. Remember to go _______ your test paper to check the grammar and spelling mistakes. a. On b. over c. off d. by 10. I hope the weather improves. _______, we'll have to cancel the picnic. a. However b. Otherwise c. Consequently d. Whereas 11. I'll never forget _______ this piece of music for the first time. a. Hear b. hearing c. to hear d. heard 12. He's never been to England, _______? a. is he b. isn't he c. has he d. hasn't he 13. Peter asked me _______. a. what time does the film start b. what time the film starts c. what time the film started d. what time did the film start 14. What benefits does TV bring about to people life? a. Programmes b. conveniences c. advantages d. experiences 15. _______ where the theater was, she asked for direction at the hotel reception. a. Not known b. Not knowing c. Have not known d. Having not known 16. He managed to repair the car _______. a. on himself b. by himself c. by his own d. his own self 17. _______ I get angry and upset, I try to take ten deep breaths. a. Until b. Whenever c. Whereas d. For 18. This room is too dark. It needs _______. a. to repaint b. repainting c. being repainted d. to be repainted it 19. _______ your age, I'd do things differently. a. If I am b. I was c. Was I d. Were I 20. That color doesn't really suit you, if you don't mind _______ so. a. I say b. saying c. my saying d. me to say 21. John wants to visit the place _______ President Ho Chi Minh left Viet Nam in 1911. a. that b. which c. where d. what 22. My brother _______ much contact with my family since he to New York. a. didn't have - moved b. hasn't had - moved c. didn't have - has moved d. hasn't had - has moved 23. I wish I _______ so I would feel safe in a boat. a. can swim b. would swim c. could swim d. swam 24. Mike is very helpful. He finds _______ in helping people. a. confidence b. relaxation c. convenience d. satisfaction 25. “Let's go for a drink." “_______.” a. Yes, please b. You're welcome c. It's all right d. That's a good idea Choose the underlined word or phrase (A, B, C or D) that needs correcting. 26. If I find some money on the street, I'd take it to the police station. A B C D 27. We reached the nearest village after walk for five hours. A B C D 28. He had his sister to help him with his homework and asked her to write the A B C essay for him. D 29. Mai's brother is studied law at one of the most well-known universities A B C in the USA. D 30. I don't think my son is not good enough to find the answer to the problem. A B C D Use the correct form of the word given in each sentence. 31. The label tells the consumers how much energy _______ each model has. (efficient) 32. You'd better learn how to protect your property from earthquakes, floods and other natural _______. (disastrous) 33. Three hundred people were made _______ by the earthquake. (home) 34. The new building looks most _______ with its huge tower. (impress) 35. You should have basic _______ on using the Internet. (instruct)

Dịch đoạn văn sau sang Tiếng Việt (ko dùng google dịch) Today, there is a TV set in nearly every home. People watch televison every day, and some people watch it from moring until night. Anmericans watch television about 35 hours a week. But is television good or bad for you? People have different answers. Some say that there is a lot of violence on TV today, the programs are terrible and people don't get any exercise because they only sit and watch TV. Others think that TV programs bring news from aroud the world, help you learn many useful things, especiall children. Thanks to televison, people learn about life on other countries, and it helps peole relax after a long day of hard work.

giúp em nha mn ơiii hình hơi nhỏ nên mn thông cảm giúp em ạ

trong bài 35 hóa 9 hãy cho mình một số cái có thể vẽ được 5 cách khác nhau

giải phương trình giúp mình với, làm ơnnn