- Mua đĩa về mà nghe 

CÔSI ta có VT<=1/xy+1/zy+1/zx. 

sau đó vẫn áp dụng bất đẳng thức cosi tùng đôi một vế phải đã cho ta sẽ đc điều phải chứng minh

In her latest article in Eathbound Science Journal, ecologist Mei Ling offers a ____ review of Paul Winthrop's research on drought resistance.

A. Critic

B. Critical

C. Criticize

D. Critically

- Chắc là không ♫

a. I'd like him bring me a packet of cigarettes.

► bring → to bring

b. I'm going to the market but I can't think about what to buy for dinner.

► but → although

c. This is a letter of my friend in Autralia.

► in → from

Cách khác: 4 < x*2 < 10 

 nên 4 :2 <x < 10:2

       2<x<5

Vậy x =3 và x=4

1. I'm afraid I've got ... my doctor today.

A. see       

B. to see

C.to see to

D. seeing [Không chọn to see vì to see chỉ được dùng trong tương lai]

2. They gave ... looking for her when it grew dark.

A. up

B. in

C. off

D. out

3. We heard her ... to her little brother yesterday evening.

A. talked

B. to talk

C. talks

D. tallk

4. Let's wait here until the rain ... up.

A. let

B. will let

C. lets

D. is letting

5. Would you mind if I ... you by your first name?

A. called

B. call

C. calls

D. am calling

5. She ( be/come ) _____will become_________ a famous artist in the future.

6. John's parents ( often / give ) _____often give__________a big presents to him on his brithday .

7. we ( often / make ) ___often make___________ chung cake on Tet holiday .

- Có

a) \(\frac{3}{4}=\frac{1}{4}+\frac{2}{4}\)

b) \(\frac{3}{4}=\frac{9}{12}=\frac{2}{12}+\frac{3}{12}+\frac{4}{12}=\frac{1}{6}+\frac{1}{4}+\frac{1}{3}\)

c) \(\frac{3}{4}=\frac{18}{24}=\frac{1}{24}+\frac{2}{24}+\frac{3}{24}+\frac{12}{24}=\frac{1}{24}+\frac{1}{12}+\frac{1}{8}+\frac{1}{2}\)