Vì |x+1| ≥0 ; |x+2| ≥ 0 ; ...|x+20| ≥ 0
⇒ x+100 ≥ 0
⇒ ( x+1 ) + ( x+2 ) + ... + ( x+20 ) = x + 100
Ta có từ 1 đến 20 có 20 số hạng
Tổng từ 1 đến 20 là (20+1) . 20 : 2 = 210
⇒ 20x + 210 = x + 100
⇒ 20x - x = -210 + 100 ( quy tắc chuyển vế)
⇒ 19x = -110
⇒ x = $\frac{-110}{19}$
TH1: `x>=-20`
Phương trình trở thành:
`x+1+x+2+x+3+...+x+20=x+100`
`(x+x+...+x)+(1+2+...+20)=x+100`
`20x-x=100-((20*21)/2)`
`19x=-110`
`x=-110/19`
TH2 : `x<=-20`
Giải tương tự ra kq : `x=10`
II. Choose the best answer for the following questions 1. _______ does your brother go fishing? He goes once a week. A. How old B. How often C. How D. What 2. Lan did not go to school yesterday_______ she was ill. A. so B. because C. but D. and 3. She _______ her homework 2 hours ago. A. is doing B. does C. did D. has done 4. _______ you been in HCM city? A. Do B. Has C. Did D. Have 5. If we reduce soil pollution,we .........................enough food to eat A. will have B. has C. have D. are having 6. They think they will stay ....the Moon ..........a short time. A. at/at B. at/for C. on/at D. on/for
Câu IV : (4,0 điểm): Cho AABC vuông tại A có B = 40°. a) So sánh các cạnh của AABC. b) Gọi D là trung điểm của AB. Qua D kẻ đường thắng vuông góc với AB cắt BC tại E. Chứng minh AADE = ABDE c) Tinh số đo EAC và chứng minh AAEC cản d) Gọi giao của AE và CD la G. Chúng minh CG=2GD. e) Trên tia đổi của tia AC lấy điểm M sao cho AM -AC. Chứng minh BA là tia phân giác của MBG
Exercise 4. Cho dạng đúng của động từ trong ngoặc 18. If Minh (get) ____ more pocket money, he (ask) ____ Lam out for dinner. 19. If we (win) ____ the lottery, we (fly) ____ to London. 20. If I (meet) ____ Brad Pitt, I (ask) ____ for his autograph. 21. If the weather (be) ____ nice, they (play) ____ football. 22. If we (go) ____ to a good restaurant, we (have) ____ a better dinner. 23. If An (learn) ____ more words, he (write) ____ a good report. 24. If the boys (take) ____ the bus to school, they (arrive) ____ on time. 25. If the teacher (explain) ____ the homework, I (do) ____ it. 26. If they (wait) ____ for another 10 minutes, they (see) ____ the pop star. 27. If the police (come) ____ earlier, they (arrest) ____ the burglar. 28. If you (buy) ____ fresh green vegetable, your salad (taste) ____ better. 29. If Alex (ask) ____ me, I (email) ____ the documents. 30. If he (speak) ____ more slowly, Peggy (understand) ____ him. 31. If we meet at 9:30, we (have) ____ plenty of time. 32. Lisa would find the milk if she (look) in the fridge. 33. The zookeeper would have punished her with a fine if she (feed) ____ the animals. 34. If you spoke louder, your classmates (understand) ____ you. 35. Dan (arrive) ____ safe if he drove slowly. 36. You (have) ____ no trouble at school if you had done your homework. 37. If you (swim) ____ in this lake, you’ll shiver from cold. 38. The door will unlock if you (press) ____ the green button.
giúp mình nhanh nhé mình caanf trước 11h 30
Choose the best answer by circling its corresponding letter A, B, C or D . 1. My dad likes _______ gardening every weekend, so we always have fresh vegetables to eat. A. making B. doing C. planting D. growing 2. We need some pork, it is the reason we go to the _________ and buy some. A. drug store B. butcher’s C. wet market D. tailor’s 3. It’s a very busy airport. There are planes _________ and landing every 5 minutes. A. going up B. taking off C. getting up D. driving off 4. After using, you should _________ the lamp to save energy. A. take off B. go off C. turn off D. get off 5. The doctor says my father will become ill _________ he stops smoking. A. until B. when C. unless D. if
nhúng 1 miếng nhôm kim loại nặng 5g vào 250ml dung dịch CuSO4 0,4M sau 1 thời gian lấy miếng nhôm ra rửa sạch phơi khô cân nặng 5,69g a) tính khối lượng đồng thoát ra bám vào miếng nhôm b) tính nồng độ mol của các chất sau phản ứng
1. Choose the word which is pronounced differently from the others. (0,25m) A. these B. brother C. think D. that 2 .Choose the word having different stress from the others(0,25m) A. collect B. pollute C. teacher D. enjoy giúp mik mik cần gấp mik hứa đánh giá 5sao kèm lời cảm ơn ạ
a)(x-37)×4+9,2=87 b)82+(x-47)×3=116 c)98:(2 × x)+1=24 Mọi người giúp em em cần gấp
giúp mình nhé cứu mình mình ccaanf gấp
Exercise 4. Cho dạng đúng của động từ trong ngoặc 1. If I (study) ______________, I (pass) ____________________ the exams. 2. If the sun (shine) __________________, we (walk) _______________ into town. 3. If he (have) ____ a temperature, he (see) ____ the doctor. 4. If my friends (come) ____, I (be) ____ very happy. 5. If she (earn) ____ a lot of money, she (fly) ____ to New York. 6. If we (travel) ____ to Hanoi, we (visit) ____ the museums. 7. If you (wear) ____ sandals in the mountains, you (slip) on the rocks. 8. If Giang (forget) ____________________ her homework, the teacher (give) ____________________________ her a low mark. 9. If they (go) ____ to the disco, they (listen) ____ to loud music. 10. If you (wait) ____ a minute, I (ask) ____ my parents. 11. If I (come) ____ home earlier, I (prepare) dinner. 12. If we (live) ____ in HCM city, my boyfriend (visit) ____ us. 13. If Tung and Thanh (be) ____ older, they (play) ____ in our football team. 14. If he (be) ____ my friend, I (invite) ____ him to my birthday party. 15. If Xuan (study) ____ harder, she (be) ____ better at school. 16. If they (have) ____enough money, they (buy) ____ a new car. 17. If you (do) ____ a paper round, you (earn) ____ a little extra money.
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