a) Chứng minh với x,y là các số dương thì: x^2/y^2 + y^2/x^2 +x/y +y/x -4 >=0 b) Chứng minh với x,y là các số khác 0 thì: x^2/y^2 + y^2/x^2 -3( x/y + y/x) +4 >=0

Hãy nêu ra 5 loại axit kém bền thường gặp( axit kém bền là axit dễ bị phân hủy ko tồn tại được lâu khi mới hình thành!!!) CÁC BN GIÚP MK VS NHA, MK ĐANG CẦN GẤP!!!

1. Introduce yourself, tell us your name, and tell us about your neighbourhood. Where is it? 2. Tell us about the neighbourhood: What is it like? What is in your neighbourhood? How are the people there? 3. Tell us if there is something you don’t like about your neighbourhood?

Tìm các số hữu tỉ a,b cho bik: x= căn 2 +1 là nghiệm của phương trình x^3 + ax^2 + b+3=0 GIÚP MK VS NH MẤY BN!!! THANKS YOU SÔ MỚT

Chứng minh (n+3)(n+6):2 với mọi n thuộc N

nguyên nhân làm thể thuỷ tinh bị phồng

mọi người trả lời giúp em mấy câu này với, xin cảm ơn ạ

Vẽ cho e Cái gì cute xíu được không:3 Thiệt là cute đó nhaaaa

Giải hết dùng em cái em xin cảm on mấy anh mấy chị mấy em mấy bạn :(((

I, READING + Choose answers A, B, C, D that match the paragraph: The world's largest animals (1) ______________ to go on feet because it allowed them to develop stronger legs and carry a great deal of body weight. Scientists have (2) _________________ the reason that many large mammals from rhinos, hippos to giraffes tend to move on their feet. This is because walking with toes and (3) _______________ can allow these animals to become larger at the same time. A study of 880 mammals found that many sized animals grew (4) _______________ at the same time they evolved from walking on flat feet to walking with feet. Dr Manabu Sakamoto, a (5) _______________ scientist at the University of Reading (UK), said that mammals grew very (6) _________________ when they began to walk like "ballerinas". The tiptoe and the legs that they developed to lead to the large mammals we know today. Besides, we also cannot see lizards eat a ton of grass. Dinosaurs are another group in (7) _________________ history that had a way of moving with tiptoe and reaching sizes of up to many tons. 1) A. evolved B. evolvement C. development D. evolution 2) A. discover B. detect C. discovered D. detected 3) A. hoof B. horseshoe C. hooves D. claw 4) A. fast B. rapidly C. quicks D. promptly 5) A. biologically B. Ecological C. biology D. biological 6) A. speedily B. quickly C. fastly D. swiftly 7) A. evolutionary B. evolution C. developmental D. evolvement