Đáp án:
Giải thích các bước giải:
Nhận xét : Dãy số 1+2+3+.......+1999 là dãy số cách đều
Số số hạng của dãy là : ( 1999 - 1 ) : 1 +1 = 1999
Dãy số 1+2+3+....+1999
Tổng các số hạng của dãy là : ( 1999 +1 ) x 1999 : 2=1999000
Chúc bạn học tốt nhé
Ảnh nguồn:nguyenthanhthao24072009
Ảnh gốc tui mong mod không xóa!!!
Exercise 1. Rewrite the following sentences in reported speech with infinitives. 39. “Don’t forget to send your uncle a birthday card tomorrow,” Mary said to her son. Mary reminded ...…………………………………………………………...................................................... 40. “Please come to our wedding,” John said to his boss. John invited …………………………………………….................................................................................. 41. “Don’t run around the edge of the swimming pool or you’ll fall in,” Susan said to her children. Susan warned ………………………………………………………............................................................... 42. “I won’t go to bed,” Ron said. Ron refused ……………………………………………….............................................................................. 43. “You should talk to your advisor,” Bill said to Linda. Bill advised ……………...…………………………....................................................................................... 44. “Take that chewing gum out of your mouth immediately!” the teacher said to Tom. The teacher ordered ……………………………………………………………….......................................... 45. “ I will bring the sandwiches to the party,” said Helen. Helen offered ................................................................................................................................................... 52. “Come to the cinema with me tonight,” he said to her. He invited ……...……………………………………….................................................................................. 53. The teacher said to us , “Do all your homework before you go to class” The teacher told ..……………………………………….................................................................................. 54. Mary said to Tom, “Send me a postcard when you come to Paris, please” Mary asked ....................................................................................................................................................... 55. He said to me, “Don’t believe everything you hear” He advised ..……………...…………………………....................................................................................... 56. James said to her boyfriend, “Come with me tonight. I’m feeling very lonely” James begged .…………...…………………………....................................................................................... 57. “Follow this car,” the detective said to the taxi-driver. The detective ordered ....................................................................................................................................... 58. “Go on, send your short story to magazine,” Adam said to Alice Adam encouraged ............................................................................................................................................ 59. The teacher said to Jim, “Would you give your book to Mary, please?” The teacher asked ............................................................................................................................................. 60. “Ok. I will not change the date of the meeting,” Mary said Mary promised .................................................................................................................................................
cho tam giác ABC vuông tại B có AB=15cm, AC=20cm, đường cao AH, đường phân giác DB(h thuộc BC; D thuộc AC) a) c/m tg ABC đồng dạng tg HBA, từ đó suy ra AH.BC=AC.AB b) tính độ dài các đoạn thẳng BC, AH, BH, c) gọi I là giao của AH và BD, tìm tỉ số S tgABD/S tgHBI d trên cạnh AB lấy điểm M, trên cạnh AC lấy điểm N sao cho BM=CN, gọi K là giao điểm của MN và BC. c/m AB/AC=KN=KM mk đg cần gấp ạ!!
8 người làm 500 sản phẩm hết 4 giờ. Hỏi cũng năng suất ấy thì 16 người làm 1000 sản phẩm hết bao lâu?
Vẽ Miki (Shugo Chara) + trong bức vẽ kí là @Mihh
I.Choose the best answer 1. _______ he is old, he wants to travel around the world. A. In spite of B. Although C. Despite D. Because 2. ________ I came to England, I couldn’t speak a work of English. A. Since B. After C. While D. Before 3. They left the house ________ saying good-bye to their mother. A. before B. after C. during D. in 4. She is looking for a new job _______ she is tired of doing a routine job day after day. A. despite B. although C. because D. All are correct 5. He’s still going to school _________ his injury. A. even though B. although C. in spite of D. even though 6. He left home early ________ he could arrive at the station on time. A. because of B. in order to C. although D. so that 7. We will wait here ______ he comes back. A. while B. until C. before D. after 8. We could reach the house ______ the road was flooded. A. although B. whether C. as if D. even 9. My mother looks _______ she is tired. Perhaps she didn’t sleep well last night. A. like B. although C. until D. as if 10. Our teacher speaks slowly _______ we may understand him. A. because B. in order to C. so that D. or 11. ________ these cars are cheap, they last a long time. A. Because B. in order that C. Although D. after 12. You should give the iron time to heat up _______ you iron your clothes. A. because B. so that C. even though D. before 13. You need good shoes to go hiking in the mountains _______ the ground is rough and hard. A. because B. so that C. before D. even though 14. ________ he is tired, he can’t work longer. A. Because B. Even though C. Although D. Beside 15. ______ he is so busy with his work, he always finds time to go to the concert every week. A. If B. Since C. Although D. Because 16. I haven’t seen Tom _____ he gave me this book. A. since B. for C. until D. Before 17. He had left _____ I came. A. when B. while C. since D. by the time 18. Our visit to Japan was delayed _____ my wife’s illness. A. because B. because of C. thanks to D. Though 19. I couldn’t unlock it ______ I had the wrong key. A. because B. so that C. although D. so 20. ______ rain or snow, there are always more than fifty thousand fans at the football games. A. Despite B. Although C. Because D. Since
Tìm m để hbpt $\left \{ {{x^{2}-2x+1-m\leq0} \atop {x^{2}-(2m+1)x+m^{2}+m\leq0}} \right.$ có nghiệm
cho mik hỏi ND CỦA BÀI VĂN NÀY LÀ J
mé thằng nào cứ báo cáo, viết câu hỏi mật lắm á. 2ly 3 xiên pò! vẽ anime chibi tức giận
lm hộ mk vs mk cần gấp cảm ơn nhiều nhé
Một bể nước hình lập phương có độ dài cạnh là 90cm .Bể nước đó có thể chứa được nhiều nhất bao nhiêu lít nước ? (biết 1l = 1 dm3 )
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