Tìm x

12 7 : x + 2 3 = 7 5

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions.

Orbis is an organisation which helps blind people of everywhere. It has built an eye hospital inside an aeroplane and flown it all over the world with an international medica team. Samantha Graham, a fourteen-year-old schoolgirl from England, went with the plane to Mongolia. Samantha tells the story of the Eukhtuul, a young Mongolian girl.

‘Last year, when Eukhtuul was walking home from school, she was attacked by boys with sticks and her eyes were badly damaged. Dr. Duffey, an Orbis doctor, said that without an operation she would never see again. I thought about all the things I do that she couldn’t, things like reading schoolbooks, watching television, seeing friends, and I realised how lucky I am.’

‘The Orbis team agreed to operate on Eukhtuul and I was allowed to watch, together with some Mongolian medical students. I prayed the operation would be successful. The next day I waited nervously with Eukhtuul while Dr. Duffey removed her bandages. “In six months your sight will be back to normal,” he said. Eukhtuul smiled, her mother cried, and I had to wipe away some tears, too!’

Now Eukhtuul wants to study hard to become a doctor. Her whole future has changed thanks to a simple operation. We should all think more about how much our sight means to us.’

What is the result of Eukhtuul's operation?

A. After some time she will see as well as before.

B. Before she recovers, she needs another operation.

C. She can see better but can never have normal eyes.

D. She can't see perfectly again.

Thực hiện phép cộng các phân thức sau 4 x 2 - 3 x + 17 x 3 - 1 + 2 x - 1 x 2 + x + 1 + 6 1 - x

Cho đường tròn (O; R) có dây BC không phải đường kính. Dựng hai tiếp tuyến tại B và C chúng cắt nhau tại A. Biết rằng   A B C ^ =   30 °  . Tính BC theo R?

A. BC = 3 R

B. BC =  2 R

C. BC = R

D. Đáp án khác