Chứng minh các mệnh đề sau bằng phương pháp phản chứng a) Nếu tổng của n số thực bằng n+1 (n≥2) thì có ít nhất một số lớn hơn 1 b) Không thể chia 7 quả cam cho 3 người, sao cho mỗi người không quá 2 quả cam

Mng giúp em câu này vs ạ, em cần gấp để chiều nộp ạ

mọi người giúp mình với mình đang cần gấp ạ vote 5 sao

Ai giúp mình vs được không ạ cần gấp lắm

Trung bình cộng hai số bằng 135. Biết một trong hai số là 246. Tìm số kia.

Choose the word that has a different stress pattern from that of the others 1. * 5 điểm purpose remote control respond 2. * 5 điểm secondary mausoleum correspondent population 3. * 5 điểm tropical separate atmosphere entertain 4. * 5 điểm engineer museum continue religion

Một electron được gia tốc bởi hiệu điện thế U bay vào một từ trường đều có cảm ứng từ B = 2.10- 3 T, theo phương vuông góc với các đường sức từ trường. Chu kỳ quay T của electron trên quỹ đạo = ?

Exercise 4: Choose the word or phrase - A, B, c or D - that best fits the blank. Mexico City is growing quickly. In 1970, the city had about 9 million people. Now it has over 17 million. All these people are causing (1) ................... . for the city. There are not (2) .................... jobs. Also, there is not enough housing. Large families have to live together in small homes. Many homes do not have water. They also do not have bathrooms or electricity. The Mexican government is (3) .................... about all these problems. It is working hard tomake (4) .................... better in the city. Why is Mexico City growing so ( 5) .................... ? Where are all these people coming from? They are coming to the city from the country. Life is hard on the farms in Mexico. Most people on farms have to live a very simple life. They have no ( 6) .................... money for modern things. People think life in the city must be (7) .................... So they leave their farms and move to Mexico City. All around the world, large cities have the same problems. One of them is air (8) .................... Mexico City has bad air. It is dirty and (9) ................... . Cars are one reason for the dirty air. Many Mexicans now own their own cars and drive in the city. The factories in the area also cause air pollution. These factories put a lot of ( 10) .................... into the air. It is not easy to clean up the air in a large city. The government has to make new laws, and everyone hasto help. 1 * A. problems B. matters C. things D. news 2 * A. much B. more C. enough D. many 3 * A. worried B. interested C. discussed D. known 4 * A. duration B. circle C. live D. life 5 * A. normal B. fast C. slow D. average 6 * A. bonus B. extra C. added D. given 7 * A. bad B. good C. better D. best 8 * A. pollution B. matter C. complaint D. comment 9 * A. noisy B. tidy C. clear D. unhealthy 10 * A. dirt B. smoke C. noise D. pollution than this one. (most)

Bài2 : Rút gọn biểu thức sau: a) x( 2x² - 3) - x²(5x + 1) + x² b, 3x (x - 2) - 5x(1-x) - 8(x³ - 3) c) $\frac{1}{2}$ x² (6x - 3) - x (x² + 1) + (x + 4)

Giúp tớ với, tớ đang cần gấp để mai nộp bài