Giúp mình câu e và câu f nha mình cảm ơn mn

Bài 2. Cho n = 29 k với k ∈ N. Với giá trị nào của k thì n là: a) Số nguyên tố; b) Hợp số; c) Không phải là số nguyên tố cũng không phải là hợp số. Bài 4. Tìm x, y ∈ N biết (x + 1)(2y – 5) = 143 Bài 5. Tìm các số tự nhiên x thỏa mãn $x^{2}$ - 2x = 0 Bài 8. Ba số tự nhiên khi chia cho 3 có các số dư khác nhau. Chứng minh rằng tổng của chúng là một số chia hết cho 3.

Energy is fundament to human beings. Many poor people in developing countries do not have modern sources of energy like electricity or natural gas, with which their life can be improved. People who live in mountainous areas have to gather wood for fuel. This takes a lot of time. For many people living in rural areas, biogas is the largest energy resource available. The main use of biogas is for cooking and heating, but it can also provide energy for public transport. As biogas is smoke-free, it helps the problem of indoor air pollution. Moreover, it is made from plant waste and animal manure. They cost almost nothing. The tendency to use renewable energy sources in developing sources in developing countries is on the increase as non-renewable ones are running out. In the future, the wind and the sun will be uses as the most important environmentally friendly energy sources. a. __________ Non-renewable sources are being used up. b. __________ Many poor people in developing countries do not have little electricity c. __________ Biogas is a new source of energy available for poor people. d. __________ Biogas creates a lot of smoke. e. __________ The new energy source is not costly. 5. Read the paragraph, then do the tasks given below. Energy is one of the problems that many people are interested in. It is not an unfamiliar word. It is heard, said, discussed day after day. It is close to everyone’s daily life. You turn on a lamp and it is energy that gives you light. You turn on a TV and it is energy that gives you pictures and sound. You ride a motorcycle and it is energy that gives you movement. You cook your meals and it is energy that gives you heat to boil rice. The problem is that the demand for energy is rising and that the price of energy is getting higher and higher. The supply of energy on earth is limited. It can not provide us forever. The shortage of energy in the future is inevitable. Therefore, saving energy is a must if we want to continue to live in a safe and sound world. a. __________ Many people aren’t interested in the problems of energy b. __________ The word “energy” is familiar and close to everyone’s daily life. c. __________ Energy is heard, said, discussed day after day. d. __________ We can’t watch TV without energy. e. __________ The supply of energy on earth is unlimited. It can provide us forever. f. __________ If we want to continue to live in a safe and sound world, we have to save energy. 6. Read the paragraph, then do the tasks given below. When Nam was twelve, his family moved to the city. At first, every thing was strange and difficult to him. Life in the city is always busy. He hated the noise and the busy roads. He hated crossing the road most. A lot of bikes, motorbikes, cars and buses coming from every direction scared him. He gets used to the life in the city now. He is no longer afraid of crossing the road but he doesn’t really like to live in the city. He prefers to live in the country. a. __________ Nam’s family moved to the city when he was twelve. b. __________ Everything was normal. c. __________ Now Nam isn’t afraid of crossing streets. d. __________ Nam likes to live in the city.

Chỉ dùng thêm dung dịch Ba(OH)2 hãy phân biệt các dung dịch : HCl , NaCl , MgCl2 và Na2SO4 , các phương tiện có đủ.

mong mọi người giúp mình giải bài này

trong mặt phẳng tọa đọ OXY cho các điểm A(1;3) B(-4;2) C (3;1) 1. tính OA ;OB;OC 2.tính dài trung tuyến AM của tam giác ABC tính chu vi ; diện tích tam giác ABC

Vẽ chibi/anime cổ vũ:3 Full màu 27 em thi rồi, chúc em thi tốt đi mn=^=

TÌm số tự nhiên n, biết: $8^{n}$ : $2^{n}$ = 4

Nét đặc sắc nhất trong văn bản tinh thần yêu nước của dân ta là gì

where do can do some sighseeing near where you live?" You should say : What place is famous for? Why do you like it?