Đáp án + Giải thích các bước giải:
Đặt `A=13+13^2+13^3+13^4+13^5+13^6`
`=> A = (13+13^2)+(13^3+13^4)+(13^5+13^6)`
`=> A = 13(1+13) + 13^3(1+13) + 13^5(1+13)`
`=> A = 13.14+13^3 . 14 + 13^5 . 14`
`=> A = 14(13 + 13^3 + 13^5)`
`=> A = 2.7(13 + 13^3 + 13^5) \ vdots 2`
`=> A \ vdots 2` (Đpcm)
`13 + 13^2 + 13^3 + 13^4 + 13^5 + 13^6`
`= (13 + 13^2) + (13^3 + 13^4) + (13^5 + 13^6)`
`= (13. 1 + 13. 13) + (13^3. 1 + 13^3. 13) + (13^5. 1 + 13^5. 13)``= 13. (1 + 13) + 13^3. (1 + 13) + 13^5. (1 + 13)`
`= 13. 14 + 13^3. 14 + 13^5. 14`
`= 14. (13 + 13^3 + 13^5)`
`= 2. 7. (13 + 13^3 + 13^5) vdots 2``=> 13 + 13^2 + 13^3 + 13^4 + 13^5 + 13^6 vdots 2``=> đpcm`
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Đường thẳng `(d): y=x-2` và parabol `(P):y=-x^2` cắt nhau tại hai điểm `E` và `F`. Tính diện tích tam giác OEF.
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V. Read the passage and choose the best word or combination of words to fill in each blank. Write your answers (A, B, C or D) in the box provided. (1.5 ms ) The word “blog” is (1) _____ “weblog”. A blog is an online diary or “log” of someone’s life, thoughts, or opinions. Anybody can (2_____ their own blog and blogging is becoming (3) _____ popular. (4) _____ “blog” into Google and you will get over 500 million hits. For (5) _____ purposes, scholars, teachers, and students create blogs as personal online study sites: places to work together and (6) _____ information and ideas. Some universities even give their students and staff free space on a server to start their own blogs. 1. A. stand for B. made from C. come to D. short for 2. A. carry B. do C. think D. create 3. A. extremely B. extreme C. hard D. hardly 4 A. Paint B. Type C. Read D. Doing 5. A. educated B. educate C. educational D. education 6. A. agree B. make C. look D. share Answers ✍ 1. 2. 3. 4. 5. 6. VI. Read the text and select the correct option. ( 1.5 ms ) Pham Tuan stepped onto Salyut 6 with a special feeling. Another record was broken: The first Vietnamese, the first Asian, stepped onto a space station. That Vietnamese man brought into space the Declaration of Independence and the will of President Ho Chi Minh as well as a national red flag with a yellow star. Pham Tuan had a desire to view Vietnam from space. During the first days of the flight, they also saw the sun that shone on the earth diagonally. Pham Tuan recognised the familiar shape of his country though the sunlight made it difficult for him. However, there were lots of clouds then. Reporters from Donev newspaper persuaded Pham Tuan not to be sad because he would have chances to enjoy it later. Victor Gorbatko had a sense of humour. Answering the question, “ What is your research astronaut (Pham Tuan) doing?”, he said that he was sitting by the window and did not want to leave it until he saw his beloved village. In fact, in his free time, Pham Tuan always sat by the window with binoculars in his hands, hoping to see the S-shape land. Somtimes, he broke the timetable to go to bed and sat at the command center to watch. After 7 days, 20 hours and 42 minutes with 142 orbits, it was time for Pham Tuan and Gorbatko to return to earth. What happened to the two astronauts after their landing was like a joyful carnival. The moving meeting took place in Star City where Pham Tuan’s father was waiting to welcome himback. What was Salyut 6? A. plane B. a train C. a spaceship D. a ship 2. It is inferred from the sentence “Another record was broken” in paragraph 1 that _______? A. Pham Tuan broke three records B. Pham Tuan had never broken any records before C. That was the first time Pham Tuan had broken a record D. Pham Tuan had broken a record before 3. He brought_________ among other things, with him into space. A. a suitcase B. his national flag C. a camera D. his family album 4. What made diffculty for him to view Vietnam clearly from space during the first days of his flight? A. Bad weather B. He didn’t have binoculars C. The sunlight and lots of clouds D. His poor eyesight 5. Who was Victor Gorbatko? A. A reporter from Donev newspapers. B. Pham Tuan’s Russian companion astronaut. C. Pham Tuan’s Russian old friend D. Pham Tuan’s brother. 6. How long was his historic flight into space? A. 7 days, 20 hoursand 42 minutes. B. 142 orbits C. 20 hours D. 42 minutes Answers ✍ 1. 2. 3. 4. 5. 6. VII. Write a new sentence as similar as possible in meaning to the original sentence, using the word(s) given: (2ms) 1. Lan was tired and sleepy so she went to bed before the game show ended. BECAUSE => ..........………………….................................................................................................................................. 2. My grandmother has recovered from her operation. GOT => ……………………………………..........……….........................................................................………… 3. People understand that Binh Dai Fortres was designed to control movement on the Perfumed River. => It ............................…………………………………….………….…......................................................... 4. Mary wanted all of us to visit Po Nagar Cham Towers after lunch. => Mary suggested ……………………………………………............…………………………………..…
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