Ta có BĐT Cô - si hai số là : $ a+b ≥ 2\sqrt[]{ab} $
$⇔ (a+b)^2 ≥ 4ab $
$⇔(a=b)^2 ≥ 0 $ ( luôn đúng )
Dấu "=" xảy ra $⇔a=b$
Ta có: $(a-b)²≥0$ $∀a,b$
⇒ $a²-2ab+b²≥0$
⇔ $a²+b²≥2ab$
⇔ $a²+2ab+b²≥4ab$
⇔ $(a+b)²≥4ab$
Với $a,b≥0$, ta có: $a+b≥2.\sqrt{ab}$
Dấu $=$ xảy ra khi $(a-b)²=0$
⇔ $a=b$
Giúp đỡ mình vớiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
2.tìm x biết rằng: ||x|-7|=x+5 3. tìm x thỏa mãn: a)|5x-3|-3x=12 b)|x^2-2x-4|+4=4x 4. tìm x thỏa mãn: a)1/1.4+ 1/4.7+ .....+ 1/97.100= |x/3| b)4/1.5+ 4/5.9+ .....+ 4/97.101= |5x-4/101| c)(1-1/2). (1-1/3). (1-1/4)......(1-1/100)= |x-1.99/100| 5. tìm tất cả các cặp số nguyên x, y thỏa mãn: 8.|x-2017|=25-y^2 làm ơn giúp mình nhanh với
Giúp với ạ mik đang cần gấp tksssss
Làm giúp mk nhé mk đang cần gấp ạ 😊
The Earth Day comes from the idea of a former US politician Gaylord Nelson. He was worried about the world pollution, and the health of plants and animals. In 1969, he decided that the world should have a special day to teach people about how to make environment better. His idea became popular and on 22 April 1970 the first Earth Day was celebrated. Since then, environmentalists have used the day to educate people about their roles in protecting our planet. Earth Day finally became a global celebration around the world. On this day, people come together to talk about global warming, protecting rare animals and saving energy sources. Question 19: The word “their” in the second paragraph refers to ______. A: politicians’ B: people’s C: Dr. Nelson’s D: environmentalists’
Mọi người giúp e với ạ, em cảm ơn
giải thích nữa nha ....................
. Sắp xếp các từ sau để được câu đúng 1 . She/ earn /works / in order to / hard / a living . =>________________________________________ 2 . I / early /avoid / go / in order to/ to / traffic jams . / work =>________________________________________ 3 . We / local food . / stop/ in order to/ for a while / enjoy =>_____________________________________ 4 . You/ in the forum . / have to /in order to /register / participate =>____________________________________ 5 . They /to /took / waste/ the taxi /so /time . / as /not =>______________________________________ 6 . his English . / in order to / He/ to/ went/ school / practice =>______________________________________
mọi người ơi , mọi người ơi , giúp mình bài này được ko vậy , nếu ai trả lời đúng sạch sẽ cho hay nhất và 5 sao nhé mọi người ơi
giúp mình với ạ mk sẽ cho 5 sao
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