1.đặt tính rồi tính(ko đặt ngang) 52,27+18,8 391,08-3,648

Chứng minh phương trình x^2+y^2=z^2 có vô số nghiệm.

1. I wish I hadn't said it. If only I could _______. A. turn the clock round B. turn the clock down C. turn the clock back D. turn the clock forward 2. I just took it _______ that he’d always be available. A. into account B. for granted C. into consideration D. easy 3. My car is getting unreliable; I think I'll trade it _______ for a new one. A. in B. off C. up D. away 4. Anne persisted _______ her search for the truth about what had happened. A. on B. about C. at D. In 5. The old houses were _______ down to make way for a block of flats. A. banged B. put C. hit D. knocked

Tìm số nguyên x,y biết a, x² - y²=91 b, x^6 +3x³ +1 =y^4 c, x² + 4x - y² =1

phân tích câu thơ: Người ngắm trăng soi ngoài cửa sổ, trăng nhòm khe cửa ngắm nhà thơ ko phải vt thành bài hay thành đoạn mà là chỉ ra nghệ thuật xong suy a ý nghĩa, nội dung ý

Cho a, b > 0 thỏa mãn: a + b < ab. Chứng minh rằng : a + b > 4 help me, please!!!

V. Change the following sentences into the passive voice. 1. The government just widened the park last year. ________________________________________________________ 2. We consider national parks ideal habitats for animals. _______________________________________________________________ 3. They have just planted ten thousand trees in this area. ________________________________________________________ 4. They are opening more national parks in this country. ________________________________________________________ 5. Do you think modern technology is destroying our nature ? ________________________________________________________ 6. We stopped poaching completely after setting up this national park. ________________________________________________________ 7. No one has found out an effective way to protect endangered animals. ________________________________________________________ 8. Should any of us check the baby animals again? ________________________________________________________ 9. The government must ban tusk sales to prevent poachers from killing elephants. ________________________________________________________ 10.People have killed their tigers for skin and bones. ________________________________________________________ 11. We should use public transport means more as a way to protect the environment. ________________________________________________________ 12. Somebody must have shot this poor rhino. ________________________________________________________ 13. The government doesn't allow hunters in national parks. ________________________________________________________ 14. With national parks, we have created safe places for animals and trees to live. ________________________________________________________ 15. They couldn't have killed the baby bear if its mother hadn't been unconscious. ________________________________________________________

Cho hình vuông ABCD có cạnh bằng 1, M là trung điểm cạnh AB. Trên đường chéo AC lấy điểm N sao cho véctơ AN = 3/4véctơ AC. Tính tổng vectoDN.vectoNC + vectoMN.vectoCB

vòi thứ nhất 5 giờ đầy bể ,vòi thứ hai chảy 4 giờ đầy bể,vòi thứ ba chảy 3 giờ thì đầy bể .Hỏi nếu 3 vòi cùng chảy thì mấy giờ sẽ đây bể

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