user-avatar
lyonshadow123
2 năm trước
a)Cho A=1/7^2 - 1/7^4 - 1/7^6 - 1/7^8 +... + 1/7^98 +1/7^100. Chứng minh rằng A<1/50 b)Giả sử có 2015 số nguyên dương a1,a2,a3,...,a2015 thỏa mãn 1/a1 + 1/a2 + 1/a3 + 1/a4 +...+ 1/a2015=1008. Chứng minh rằng có ít nhất 2 trong 2015 số nguyên dương đã cho bằng nhau
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

I.Choose the best answer 1.How long ..........Jane ? –Since she was a child. A.do you know B.did you know C.had you know D.have you known 2.Although it will be more...to shop in the new mall, some people in the neighborhood are not happy A.comfortable B.inconvenient C.difficult D.different 3.There were a lot of people on the bus. It was ............than usual. A.as crowded B.more crowded C.so crowded D.much crowded 4.The shirt is ..........as that one. A.as expensive B.expensive C.the same expensive D.more expensive. 5.Mary looks............her mother. A.as B.the same C.like D.as same as 6.My neighbor.......to me ........more than two months. A.didn’t talk/ since B.doesn’t talk/ for C.hasn’t talked/for D.haven’t talked/for 7.She ..........time to do any shopping.........last Sunday. A.doesn’t have/ since B.hasn’t had/ for C.hasn’t had/ since D.didn’t have/for 8.John...........for 3 jobs.........he left school last year. A.had applied/ since B.applied/ since C.has applied/ for D.has applied/ since 9.I .........to the office every day last week. A.drove B.drive C.have drived D.had drived 10.Look at Tom’s suit. Is it ...........mine? A.the same style that B.the same style than C.the same style as D.as same as 11.The ........of the small stores in the neighborhood are especially worried. A.shop-keepers B.shoppers C.owners D.shop-assistants 12.Customers won’t mind the.......outside. A.weather B.climate C.cold D.heat 13.It is very different from the .........shopping area. A.older B.being C.present D.now 14.The stores in the mall will offer a wide ..........of products and goods. A.selection B.choice C.difference D.possibility 15.And some of products are at cheaper............ A.prizes B.costs C.prices D.charges 16. Do you want to send this letter airmail or _________? A. mail B. surface mail C. e-mail D. Taste 17. The garden is the same __________ the one I saw last week. A. than B. from C. as D.to 18.The Maori in New Zealand greet each other by ……………………….. their noses. A. punching B. touching C. blowing D. hitting 19. Australia is composed of seven ………………….. A. nations ​B. countries​C. states D. cities 20.There is a red maple leaf on the ………………… of Canada. A. flag B. banner C. money D. poster

2018 © Loga - Không Ngừng Sáng Tạo - Bùng Cháy Đam Mê
Loga Team