Rút gọn biểu thức:
\(A=\frac{1}{\sqrt{1}-\sqrt{2}}-\frac{1}{\sqrt{2}-\sqrt{3}}+\frac{1}{\sqrt{3}-\sqrt{4}}-\frac{1}{\sqrt{4}-\sqrt{5}}\)
\(B=\left(\frac{5-\sqrt{5}}{\sqrt{5}}-2\right)\left(\frac{4}{1+\sqrt{5}}+4\right)\)
\(C=\left(\frac{3+2\sqrt{3}}{\sqrt{3}+2}+\frac{2+\sqrt{2}}{\sqrt{2}+1}\right):\left(1:\frac{1}{\sqrt{2}+\sqrt{3}}\right)\)
\(D=2\sqrt{50}-\frac{1}{\sqrt{2}-1}+4\sqrt{\frac{9}{2}}-\sqrt{3-2\sqrt{2}}\)
Combine the idea, using a clause of purpose
7. Please arrive early. We want to be able to start the meeting on time.
8. I slowed down. I wanted the car behind to be able to overtake.
9. Jackson is planning to take a semester off. He wants to travel in Europe.
10. The man spoke very slowly. He wanted me to understand what he said.
11. I whispered. I didn't want anybody else to hear our conversation.
12. I'll give you a map. I want you to find the way all right.
13. Please be quiet. I want to be able to hear what Sharon is saying.
14. The little boy pretended to be sick. He wante to stay home from school.
15. I turned off the TV. I wanted my roomate to study in peace and quiet.