P=1/1 ×2+1/2 ×3+1/3 ×4............+1/2018 ×2019

cho tam giác ABC nhọn . AB là đường cao của BC. BE là đường cao của AE. AD cắt BE tại H.F là giao điểm của CH và AB.chứng minh HD/AD+HE/BE+HF/CF=1

bài 1: Tìm x biết. a) 7.x+3.x= 2010 b) ( x-6).(x-12)=0 bài 2: Tìm số tự nhiên x,y biết: a) xy -2x = 5 b) x+(x+1)+ (x+2)+ ... +(x+100 )= 10100

Tính giá trị của đa thức. A=x^7-80x^6+8x^5-80x^4+......+80x-5 với x=79 B=x^10-13x^9+13x^8-13x^7+.....+13x^2-13x+10 mn cố giúp mk chi tiết để dễ hiểu được mk xin cảm ơn !

21. This is ______ the best pizza that I’ve eaten – I can’t remember having one as tasty as this before. A. rarely B. barely C. surely D. mainly 22. The line that divides North and South Korea is the most ______ armed border in the world. A. nearly B. formerly C. kindly D. heavily 23. The streets were ______ wide enough for two people to pass each other. A. narrowly B. barely C. strictly D. closely 24. They sacked the head of marketing because he was ______ inefficient. A. relatively B. deadly C. hopelessly D. moderately 25. The computer has changed the world ______. A. irreplaceably B. irredeemably C. irrevocably D. irreparably 26. The changes in this city have occurred ______. A. with swiftness B. rapidly C. in rapid ways D. none is correct 27. I'm afraid I haven't read that book ______. A. already B. again C. ever D. yet 28. He responded to my question ______. A. in polite B. polite C. politely D. impolite 29. A breeze _______ touched my face. A. gentle B. gently C. gentler D. in gently 30. Bill is a harder worker. He works ______ than Joe. A. harder B. more hard C. more hardly D. hardier

III. Choose A, B, C or D to indicate the correct answer to each of the following questions. 1. The lights ______ dimmed for a few seconds. A. infallibly B. inexplicably C. indirectly D. ineffectively 2. The algae multiply ______ to produce what is called an algal bloom. A. chronologically B. temporarily C. efficiently D. swiftly 3. The documentary film about World War II makes no attempt to be ______ accurate. A. incidentally B. truthfully C. timelessly D. historically 4. She responded ______ to my difficult question, making me impressed with her knowledge. A. hastily B. nearly C. closely D. instantaneously 5. It is suspected the paintwork has been ______ scratched, but no evidence of the culprit has been found A. willingly B. accidentally C. deliberately D. explicitly 6. I’ll only be working here ______ for a couple of weeks A. seasonally B. temporarily C. timely D. simultaneously 7. She stood ______ still, not making a sound. A. completely B. mainly C. soundly D. intactly 8. He had ______ reached twenty when he was exiled and his formal education ended - except for whatever his father taught him. A. ever B. almost C. barely D. nearly 9. Her mother will ______ stay with them until she's made a full recovery. A. apparently B. imaginably C. necessarily D. presumably 10. They met at university and fell ______ in love. A. literally B. specially C. apparently D. hopelessly 11. He is ______ one of the finest baseball players ever A. inexcusably B. indiscreetly C. inevitably D. indisputably 12. I visit my grandmother ______, but not as often as I’d like to. A. eventually B. widely C. occasionally D. extensively 13. In the summertime, tomatoes are ______ available, since it’s the best season for them to mature in. A. solely B. shortly C. warmly D. readily 14. The Portuguese and Galician languages are ______ the same, although there are important differences between them. A. accurately B. specially C. precisely D. roughly 15. Francesca recounted the details of her vacation so ______ that we were able to picture exactly what she’d done. A. vividly B. presently C. punctually D. obviously 16. Sarah is ______ qualified so I’m sure she will get the job. A. completely B. amply C. fully D. wholly 17. Although the police suspected that the fire had been started ______, they couldn’t prove it. A. increasingly B. constantly C. deliberately D. precisely 18. There isn’t much information available ______ about the cause of the fire. A. far more B. so much C. rather than D. as yet 19. Rebecca is ______ still somewhere inside the building, but we can’t be certain that our information is correct. A. apparently B. accidentally C. mainly D. definitely 20. This is ______ the book you have to read, but, since you weren’t sure of the title, it may not be. A. especially B. literally C. necessarily D. presumably

Chọn đáp án đúng và dịch sang tiếng việt

Hai địa điểm A và B cách nhau 100 km. 1 người đi xe đạp từ A, 1 người đi xe đạp từ B khởi hành cùng 1 lúc và dự tính sau 5 giờ thì sẽ gặp nhau. Nhưng sau khi đi được 1 giờ 40 phút người đi từ B phải dừng lại sửa xe mất 40 phút rồi mới tiếp tục đi và phải sau 5 giờ 22 phút kể từ lúc khởi hành họ mới gặp nhau. Tính vận tốc mỗi người.

Các bạn ơi giúp mình bài này vs : 1. Tính: a ) A = ( 50 ² + 48 ² + ...... + 2 ² ) - ( 49 ² + 47 ² + ..... + 1 ) b ) B = ( 1,35 ³ + 2,65 ³ + 4,05 . 10,6 ) . ( 1,35 ² + 2,7 . 2,65 + 2,65 ) ² Các bạn ơi mình ms vào lớp 8 nên giải đầy đủ tí nhá ^^

nửa chu vi mảnh vườn hình chữ nhật là 20m chiều dài hơn chiều rộng 4m tính S mảnh vườn người ta xây rào xung quanh mảnh vườn biết chiều cao là 1,2 m và lối đi chừa 2m tính S rào