Đáp án:
`1+2^3+2^6+...+2^300=[2^303-1]/7`
Giải thích các bước giải:
Đặt `S=1+2^3+2^6+...+2^300``=>2^3.S=2^3+2^6+...+2^303``=>8S-S=(2^3+2^6+...+2^303)-(1+2^3+2^6+...+2^300)``=>7S=2^303-1``=>S=[2^303-1]/7`Vậy `S=[2^303-1]/7`
giải thích các bước giải :
Đặt `A=1+2^3+2^6+...+2^300`
`2^3A=2^3+2^6+2^9+...+2^303`
`2^3A-A=2^3+2^6+2^9+...+2^303-1-2^3-2^6-...-2^300`
`(2^3-1)A=-1+2^303`
`7A=2^303-1`
`A=(2^303-1)/7`
chứng minh biểu thức luôn dương hay âm với mọi x ∈ R a, x^2-6x+10>0 b, x^2-4x+7>0 c, x^2-x+1>0 d, -x^2+4x-5<0 e, -x^2 -3x -4<0 g, -x^2 -8x+3<0 GIẢI GIÚP EM VS Ạ
Bày cho mik với,nhưng phải đúng rồi mik sẽ cho sao và cám ơn
Chọn thì thích hợp nhất để hoàn thành các câu sau: 28. The train ______ when I ______ at the station. A. already left / had arrived B. already had left / arrived C. left already / had arrived D. had already left / arrived 29. Everyone was asleep when the enemy _____________ A. had attacked B. attacked C. was attacking D. attacking 30. Don't make noise. My mother ________________with her friends. A. talked B. talks C. is talking D. was talking 31. She ______ the piano since she ______ ten years old. A. played / was B. has played / has been C. has played / was D. had played / was 32. Up to now, I _________________ a lot of information about her. A. learnt B. would learn C. learn D. have learnt 33. Mary ___________ in London for 15 years. A. lives B. was living C. is living D. has lived 34. We were disappointed that most guests ___________ when we arrived at the party. A. had left B. has left C. left D. leave 35. He never goes home before he ______ his work. A. finished B. has finished C. had finished D. finishing 36. Before cars ______, people ______ horses and bicycles. A. were discovered / had used B. has been discovered / have been using C. is discovered / using D. discovering / used
136.23+136.17- 40.36. 66.25+5.66+66.14+33.66
calli;chúc mừng sinh nhật tôi nl:cô đơn với mùa covid
F = 199^4 - 181^4 chia hết cho 2 và 5 G = 10^25 + 26 chia hết cho 2 và 9
Giúp e mấy câu e chưa làm ạ .... e cần gấp
Bài 3 cho B=$\frac{6n+3}{3n-2}$ a, Tìm n để B=$\frac{3}{2}$ b,Tìm n ∈ z để B nhận giá trị nguyên Hoi khó hứa cho hay nhất
chỉ ghi đáp án [Tổng: 2 bài (15 câu: 10 câu khoanh, 5 câu điền từ)] I. Circle best option A, B, C or D to complete the following sentences. (10pts) 1. I feel tired. I'd like __________. A. to sit down B. to run C. some noodles D. some fish 2. __________her lips full or thin? A. Do B. Does C. Are D. Is 3. This sign says “Stop!”. We go straight ahead. A. can B. should C. must D. mustn’t 4. Mr. Nam gets up at 7.00 and eats __________. A. a big breakfast B. big breakfast C. the big breakfast D. a breakfast big 5. Mr. Quang and the farmer are loading the truck __________vegetables. A. on B. with C. at D. of 6. The weather is __________today than yesterday. A. so better B. very better C. too better D. much better 7. __________? ~ We play badminton and swim. A. What sports do you and your brother like? B. Which sports do you and your brother play? C. When do you and your brother play sports? D. What are you and your brother doing? 8. There is __________rice in the jar. We can’t cook rice now. A. a little B. little C. a few D. few 9. Would you like __________noodles? ~ I’m full. I don’t want __________more. A. any/ any B. some/ some C. any/ some D. some/ any 10. I’m going to the __________now. I want to buy some bread. A. post office B. drugstore C. bakery D. toy store II. Use the words given in brackets to form a word that fits in the space. (5pts) 1. At an intersection, you must slow down. It is a very ...................... place. (danger) 2. Her ...................... are small and white. (tooth) 3. Air ...................... is a big problem in many cities in the world. (pollute) 4. His ...................... are in the yard. They are skipping together. (child) 5. In my ......................, there is a park with many trees and flowers. (neighbor)
Viết cho mình chữ Quê :))) Calli nhé Có meme mới :)))
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