x + 2x + 3x + 4x +...+ 100x = 5050
(x+1)(x+2)(x+3).....(x+100)=5050
x.(1+2+3+...+100)=5050
x.5050=5050
x=1
Vậy x bằng 1
x+2x+3x+...+100x=5050
⇒x(1+2+3+...+100)=5050
ta có từ 1 đến 100 có (100-1):1+1=100(số)
⇒ tổng 1+2+3+...+100=$\frac{(1+100)*100}{2}$ =5050
⇒x*5050=5050
⇒x=5050÷5050=1
Vậy x=1
Giữa mình vs mình cảm ơn trước
31. On the official flag of Canada, we can see__________. A. a crescent moon B. four red stars C. a red maple leaf D. white stripes 32.What is one of the most famous landmarks in Australia? A. Leaning Tower of Pisa B. Great Barrier Reef C. Statue of Liberty D. Machu Picchu 33. What is the name of the most famous clock in Britain? A. Big Clock B. Big John C.Big Apple D. Big Ben 34. Which country does not have a star on its flag? A. The United Kingdom B. The United States C. New Zealand D. Singapore 35. Which country is an island city-state? A. Scotland B. Wales C. Singapore D. Australia 36. English__________ from a Proto-Indo-European language about 5,000 years ago. A. derives B. derived C. is deriving D. has derived 37. Since 2005, India__________ the world’s largest English-speaking population. A. has B. is having C. had D. has had 38. The United Kingdom__________ of Great Britain and Northern Ireland. A. consists B. is consisted C. has consisted D. consisted 39. English__________ around the world by children in school as a foreign language. A. has learned B. is learning C. is learned D. learned 40. You’d better go to bed early tonight. The plane__________ at 6 o’clock tomorrow morning so we’ll have to be up by 4.30! A. will leave B. leaves C. leave D. is leaving 41. Over the past five years, Australia’s population__________ by 1.86 million people. A. increases B. is increasing C. has increased D. is increased 42. I’m sorry. I can’t meet up this weekend. We__________ to Wales on Friday. A. go B. are going C. will go D. has gone 43. In the 16th century, French and British settlers__________ in Canada. A. arrive B. have arrived C. was arriving D. arrived 44. __________ that there are no wild snakes in Ireland? A. Do you know B. Are you knowing C. Elave you known D. Did you know 45. The Statue of Liberty, an American Symbol of freedom, __________ in France. A. actually made B. was actually made C. has actually made D. makes actually 46. The Disney World__________ in the City of Orlando, which is in the State of Florida. A. locates B. is locating C. is located D. located 47. Nowadays, Canada__________ against the influence of the foreign cultures, especially of the us one. A. struggled B. is struggling C. was struggling D. has struggled 48. Indian Disney Channel__________ Tom and Jerry Kids at 7 pm. A. shows B. is showing C. is shown D. has shown 49. My family__________ in Chicago for more than 20 years. A. live B. are living C. were D. have been 50. Residents from Liverpool speak English__________ a different accent. A. with B. as C. on D. under
Cho tam giác đều MPQ có điểm O nằm bên trong tam giác MPQ thỏa mãn OM^2=OP^2+OQ^2. Tính số đo POQ
?.....,:'/.,';\-==...............................................................................
Xét tính liên tục của các hàm số sau trên tập xác định của chúng: (xét tính liên tục trên khoảng)
Cho 15,3 gam nhô tác dụng vs 8,67 l khí ôxy đktc A) viết PTHH xảy ra? B) tính khối lượng các chất sau khiu phản ứng kết thúc
Viết thành câu mệnh đề dùm mk với ạ
Giúp mk mấy bai nay nha 🙏🏻🙏🏻🙏🏻✍🏻😰😥🥺 Mk đang cần nha ?!
Giúp em với giải hộ em!!!! Bài 6 ạ!
Bài 4 : Tính nhanh A=(-10)+20+(-30)+40+......+(-90)+100 B=(-5)+10+(-15)+.......+(-95)+100 C=1-2+3-4+5-.....+99-100 D=2+(-4)+6+(-8)+......+98-100 E=3+(-6)+9+(-12)+.....+97+(-100) F=1-3+5-7+....+97-99
Loga.vn - Cộng Đồng Luyện Thi Trực Tuyến