Đáp án: B<3/5
Giải thích các bước giải: Ta có 1/61+1/72+1/83+1/94<1/60*4=1/15
1/16+1/19+1/21<1/15*3=3/15
1/3=5/15
Do đó B<1/15+3/15+5/15+9/15=3/5
Vậy B<3/5
Đáp án+Giải thích các bước giải:
`B = B = 1/3 +(1/16 + 1/19 + 1/21) + ( 1/61 + 1/72 + 1/83 + 1/94)`
`< 1/3 + (15/15 + 15/15 + 15/15) + ( 1/60 + 1/60 + 1/60 )`
`<1/3 + 3/15 + 4/60 = 5/15 + 3/15 + 1/15 = 3/5`
`⇒ B < 3/5`
`@HaiZZZ@`
Bài 1: Cho tam giác ABC cân tại A. Tia phân giác góc A cắt BC tại M. a) Chứng minh: AMB = AMC và AM vuông góc BC. b) Từ M kẻ MH vuông góc với AB tại H và MK vuông góc với AC tại K. Chứng minh: MH = MK. c) Chứng minh: MA là tia phân giác của góc HMK. d) Chứng minh: HK // BC. e) Qua A kẻ đường thẳng song song với BC, cắt MH và MK lần lượt tại E và F. Chứng minh: MEF cân.
Giúp em bài này nha anh chị ơi Em sẽ vote 5sao +cảm ơn+ câu trả lời hay nhất nha Các chuyên gia toán vào giúp em ạ Em sẽ trả ơn đầy đủ
Fill each blank with a word from the box: accidents ,break , vehicle, across, Rules, it, feels, after 1. What ________________ you do last Sunday? 2. I stayed at home and looked ____________ my younger brother yesterday. 3. He lives in a small village in the mountains so he never ________________ worried about traffic jams. 4. You should remember to walk __________ the streets at the zebra crossings. 5. Does your bike ever ________________ down on the way to school? 6. We must always obey traffic ________________ for our safety. 7. How far is ________________ from your house to the bus stop? 8. There did not use to be many ___________ on the roads in my hometown. 9. He used to ________________ a tricycle when he was three years old. 10. Now there are more traffic _________ than there used to be in this city.
Tìm giá trị m để hệ phương trình trên có nghiệm duy nhất
In Canada and the United States, one of the most popular days in the year is Halloween. Halloween is on October 31st. It’s a day when some people dress up in strange or unusual costumes. For example, they may dress up to look like an animal, a person from a book or movie or a famous person from history. In some places, children go to school in their Halloween costumes. After dark, many young children put on their costumes and visit their neighbours. They knock on the door and shout “Trick or treat!”, then the neighbours give them some candy or chocolate, and the children go on to the next house. Adults also enjoy dressing up for Halloween. There are usually Halloween parties in the evening and usually there is a prize for the best or most unusual costume. 1. What is one of the most popular days in the year in Canada and the United States? …………………………………………………………………………………………………………….. 2. Who do some people dress up to look like on Halloween? ……………………………………………………………………………………………………………. 3. What do some children in some places in Canada and the United States wear when they go to school on Halloween? ……………………………………………………………………………………………………………. 4. What do many young children do in the Halloween’s evening? ……………………………………………………………………………………………………………. 5. What are usually there in the Halloween’s evening? …………………………………………………………………………………………………………….
Exercise 2: Combine these sentences with who , whom , which. 1. I thanked the woman. She helped me. 2. She is the most intelligent woman. I’ve ever met this woman. 3. The doctor is famous. You visited him yesterday. 4. Do you know the music? It is being played on the radio. 5. These children are orphans. She is taking care of these children. 6. She couldn’t come to the party. This is a pity. 7. The man answered the phone. He said Tom was out. 8. Who is the woman? We met her here last year. 9. Try to read the book . I gave it to you yesterday. 10. A typhoon is a violet tropical storm. It can cause great destruction. 11. Her mother listened to the news on T.V. She was interested in weather forecasts. 12. Hoa took some change. She wanted to buy some drink. 13. The boys are interested in football. It is a popular game all over the world. 14. My classmates had so much fun at the carnival. They wanted to see it again. 15. We visited the monument. It was built a hundred years ago. 16. Minh went back home. He forgot to turn off the faucet. 17. Mai wants to drink some medicine. She has a headache. 18. Children like to eat cake. It can cause toothache if they have too much everyday. 19. Her mom made a delicious for the family. She was a cook in a restaurant. 20. The boy gave his parents big hugs before he left. He went abroad to study.
Một hình trụ có bán kính đáy là 8cm , diện tích xung quanh = 400 cm^2 . Tính chiều cao của hình trụ
Giải hộ em 😗😗😗😗😗😗😗😗😗😗😗😗😗😗😗😗😗😗
Giúp mình câu khí C với ạ Mình cảm ơn
7x+3chia hết cho x-2 Giúp vs ạ
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