Thực hiện các phép tính sau:

b) \(\sqrt{7-2\sqrt{10}}-\sqrt{7+2\sqrt{10}}\)

e) \(\sqrt{17-12\sqrt{2}}+\sqrt{9+4\sqrt{2}}\)

f) \(\sqrt{6-4\sqrt{2}}+\sqrt{22-12\sqrt{2}}\)

III. REWRITE

4. The air in the country is polluted, but people like to live there.

-> Though

6. If you passed the exam, your parents would be very happy.

-> because

9. The movie was so funny that we couldn't stop laughing.

-> It was such

10. No one could move the piano. It was very heavy.

-> The piano was too

IV. Clauses of Reason: Because, Because of, As a result of, As a consequence

11. Peter didn't go to school yesterday because he was sick.-> Because of .............

12. Mary went to bed early because she felt tired. -> Because of ....................

13. She didn't go to the circus with Betty because she had a cold.-> Because of ...............

14. Iohn succeeded in his exam because he worked hard. -> Because of ..................

15. She stayed at home because her mother was sick. -> Because of ..................

16. I like him because his father is kind to me. -> Because of ....................

17. I couldn't do the test because it was difficult. -> Because of ....................

VII. Hoàn thành những câu sau sử dụng cụm từ hay mệnh đề chỉ mục đích.

1. He climbed the tree __________ get a better view.

2. You should get up early ________ you will have time to review your lesson.

3. Some young people like to earn their own living __________ they will be independent of their parents.

4. We should do morning exercise regularly _____________ improve our health.

Cho ΔABC, góc A = 90^o, đường cao AH. CMR:

a) AB² = BH . BC

b) AC² = CH . BC

c) AH . BC = AB . BC

d) AH² = HB . HC

e) \(\frac{1}{AH^2}=\frac{1}{AB^2}+\frac{1}{AC^2}\)