Tim giá trị lớn nhất của biểu thức:

\(A=5-8x-x^2\)

\(B=4x-x^2+1\)

Tìm giá trị nhỏ nhất của biểu thức:

\(A=x^2-4x+1\)

\(B=4x^2+4x+11\)

Choose the correct answer.

1. Have you ever............. to London?

A. be B. being C. been D. gone

2. People in Tokyo are very polite............. friendly.

A. or B. and C. But D. so

3. Do you know........... drink in Viet Nam?

A. popular B.more popular C. more and more popular D. the most popular

4. When we were in Stockholm, we had coffee and cakes.........a coffee shop.............the Old Town.

A. on - on B. at - at C. in - in D. on - at

5. The Eiffel Tower is the most............... landmark in the world.

A. visit B. visiting C. visited D. to visit

6. Britain's most common................. activities are watching TV and films, and listening to the radio.

A. free B. leisure C. good D. popular

7. "I have been to Nha Trang.............. . How about you?"

A. one B. two C. two times D. twice

8. Do you have...............in Da Lat during your holiday?

A. time B. good time C. good a time D. a good time

9. Nha Trang has an............. atmosphere of a young, ............ city.

A. exciting - growing B. excited - grown C. exciting - grown D. excited - growing

10. That city is most famous............ its fashion shops.

A. to B. with C. for D. of

Chứng minh rằng các biểu thức sau luôn luôn dương với mọi x, y:

\(A=x\left(x-6\right)+10\)

\(B=x^2-2x+9y^2-6y+3\)

bị điên

bố 39 tuổi