Bài 3: Giải bài toán bằng cách lập phương trình Một vòi nước chảy vào bể không có nước. Cùng lúc đó một vòi nước khác chảy từ bể ra. Mỗi giờ lượng nước vòi chảy ra bằng 4/5 lượng nước chảy vào. Sau 5 giờ thì bên trong bể đạt tới 1/8 dung tích bể. Hỏi nếu bể không có nước mà chỉ mở vòi chảy vào thì sau bao lâu thì đầy bể? Câu 6 (2 đ) : Cho tam giác ABC vuông tại A, có AB = 3cm; AC = 4cm. a/ Tính độ dài BC. b/ Hai đường trung tuyến AM và BN cắt nhau tại G. Tính độ dài AG. Câu 3: (1,5 điểm) Một người đi xe máy từ Viên Thành đến Vinh với vận tốc 40 km/h. Lúc về người đó uống rượu nên đi nhanh hơn với vận tốc 70 km/h và thời gian về cũng ít hơn thời gian đi 45 phút. Tính quãng đường Viên Thành tới Vinh.

Các câu hỏi liên quan

Except for a few unfortunate individuals, no law in this world can go against the fact that for most of us our family is an essential part of our lives. The moment you enter this cruel world, where each man is for himself, there are some near and dear ones out there who will do anything to ensure your happiness. We are nothing more than a vulnerable and fragile object, without someone taking care of us on our arrival in this world. Despite all the odds, your family will take care of your well-being, and try their best to provide you the greatest comforts in the world. No one out there, except your family must forgive the endless number of mistakes you may make in your life. Apart from teaching you forgive and forget lessons, they are always there for you, when you need them the most. Family is the only place where children study a lot after school. In school, teachers teach children about the subjects which will help them to find a good job in future. But at home, parents teach children about good habits. They are not only the elements which help the children to shape their personalities but they also prepare them a sustainable and bright future. A good family makes a greater society. Father, mother, children have to work in order to build a strong family. If any one of them fail, the whole family may collapse. The good name of the whole family can be ruined by a single member of the family. In order to avoid that unhappy scenario, every family member has to work hard and try their best. As a result, they will set good examples for the whole society. Families impacts very much on society and societies create countries. 124. According to the passage, which of the following is NOT true? A. Family is a vital part of your life. B. Not everyone has a family. C. We will effortlessly be damaged without our family. D. Some laws in the world may oppose the functions ot family. 125. In the writer's opinion, ____. A. it is not the function of the family to make sure we are happy B. your family will be with you regardless of difficulties C. family creates some easily-spoilt creatures D. people can be easily forgiven by people around 126. To children, family plays a role in ____. A. teaching them academic subjects B. developing their personal traits C. helping them to find a good job D. encouraging them to study a lot at school 127. The word "They" in the passage refers to ____. A. children B. teachers C. good habits D. parents I28. The word "ruined” in the passage is closest in meaning to ____. A. destroyed B. saved C. built D. constructed 129. According to the passage, which of the following is true about the relation between family and society? A. When a family fails, the whole society falls down. B. A family member will be unhappy to fry his best. C. Family members have responsibilities to set good examples. D. Strong families build a wealthy society. 130. Which of the following is the best title for the passage? A. Educational role ot family B. The importance of family C. Family and society D. The birth of fragile object

Lorna: I might retire early. I don’t know. I'm 55 and my husband retired last year. He spends most of his time in the garden. I’d really like to be there with him though I am not quite fond of the tasks. I'm definitely going to learn a new language. I hale going abroad and speaking English. Cass: I’m only 26, so I’m not going to retire soon! In fact I want to have more chances to earn our living. Jamie and I are going to have a baby next year and we're really excited about that. We want to have a big family and live in a big house. Then, when I retire my children and grandchildren will all be able to stay. Sue: Well, Roger and I don't agree about retiring. I love work and I don't want to retire! I know I won’t have anything to do. Roger: I asked my boss at work recently and I might be able to retire next year. I might buy a house in France and spend the time that my family deserved to have with me long before. I'd love to have my first long-awaited visit to Paris with my wife one day. Linda: I want to retire as soon as possible. I have three sons and now I don’t even have time to play with them. They will become mature very soon and don’t want to spend quality time with me. I can't stand the thought. 119. The reason Lorna looks forward to her retirement is because ____. A. her husband has already retired B. she likes doing gardening C. she hates travelling abroad D. she likes to learn English 120. Which of the following is NOT true about Cass? A. His baby is born the following year. B. He wants his family to live in a big house. C. He wants to retire soon. D. He wants to earn more money. 121. Who does NOT want to retire shortly? A. Linda B. Sue C. Roger D. Lorna 121. Roger ____. A. has spent enough time with his family already B. will ask his boss for retirement next year C. has never been to Paris before D. doesn’t want to go to Paris 122. The word “mature” in the passage is closest in meaning to ____. A. old B. grown-up C. childish D. young