Giúp mik vs, cảm ơn nha( nhanh nha)

Cho mình hỏi sao m<= 0 lại suy ra y' >= 0 và m>0 => y'=0 ạ

1 there ...an increase in road accidents in the city over the past four year A have been B has been C was D would be 2 The tourists.....by the beauty of cave A impressed B are impressed C were impressed D were impressing Giải thích vì sao chọn luôn ạ

Tính giá trị của x , biết 3x . (8x-4)-6x . (4x-3)=30

Các bác giải thích cho em hiểu với ạ

Thu gọn đa thức 1 biến 4x^2-5x-3x^4-5-7x^2+6x^4+8x+8

Cho 23,2 g Fe3O4 tác dụng hoàn toàn với 200g dung dịch HCl 3,65% a) tính khối lượng chất dư b) tính khối lượng muối sau phản ứng c) tính nồng độ % các chất trong dung dịch sau phản ứng

251. The furniture(A) in my grandmother's(B) houses are(C) very beautiful(D). 252. Either(A) the doctor or(B) the nurses takes(C) care of(D) the patients. 253. It requires(A) practice to reading(B) a foreign language quickly(C) and well(D). 254. Working(A) provide(B) people with(C) personal satisfaction as well as(D) money. 255.My computer helps(A) me manage my time better, but it is not as personal like a phone call. 256. When young (A), my mother had to(B) work very hardly(C) to earn(D) money. 257. The first(A) postage stamps(B) issued(C) in New York City in(D) 1842. 258. Ho Chi Minh city, which named is after(B) president Ho Chi Minh, is(C) quite a young city(D). That is(A) Mr Anderson, whom(B) taught me the first(C) lessons of computer skills(D). 260. His(A) grandmother and his uncle took care for(B) him after(C) his parents died(D). 261. Every human typically(A) have(B) twenty-three pairs of(C) chromosomes in most(D) cells. 262. He stopped to smoke(A) because it is(B) harmful(C) for(D) his health. 263. Not everyone(A) realizes that(B) the most largest(C) organ of the human(D) body is the skin. 264.(A) Many teachers have devoted (B) their lives (C) to teaching (D) therefore teaching is not a well-paid job. 265.People (A) depend unlimited (B) energy to power (C) their everyday (D) lives. 266.Lack o f(A) properly physical exercise (B) can cause (C) tiredness and (D) poor general health. 267.They are (A) going to build (B) the town square (C) next this (D) area 268.The train will (A) be leaving (B) on five minutes (C) so you'd (D) better hurry up 269. (A) The most you (B) learn, (C) the more knowledge (D) you get. 270. You are reminded (A) once again (B) of the author's love (C) of (D) a sea. 271. They (A) can speak English and (B) use a computer (C) so as to they (D) can easily get a good job. 272. How much times did Rick and Jennifer have to do the experiment before they obtained the results they had been expecting. 273. Each of the students in the accounting class has to type their own research paper this semester. 274. Mrs. Stevens, along with her cousins from New Mexico, are planning to attend the festivities. 275. They are going to have to leave soon and so do we. 276. Dresses, skirts, shoes and children's clothing are advertised at great reduced prices this week. 278. The government requires that a census be taken every ten years so accurate statistics may be compiled 279. To the man who worked so hard on the project, the news was profound disappointing 280. Anyone reproducing copyrighted works without permission of the holders of the copyrights are breaking the law

Dân số Việt Nam năm 2019 là 96462106 người.Năm 2020,dân số so với năm 2019.Tính dân số Việt Nam năm 2020.

1. Một cái bể hình hộp chữ nhật dài 4m , rộng 2.5m và cao 2m đã chứa 1/4 bể nước . Người ta cho vòi nước chảy vào bể , mỗi phút chảy được 60dm3 . Thời gian bể đầy nước là ? 2. Một miếng xốp hình hộp chữ nhật có chiều dài 1.8dm , chiều rộng 1.2 dm và chiều cao 9cm . Nếu cắt miếng xốp đó thành các hình lập phương nhỏ , mỗi cạnh 3cm thì được bao nhiêu hình ? 3. Tìm x $\frac{6}{x}$ + $\frac{1}{2}$ = 2