1 How long do you live in HN

2 How often did you go to the movies

3 What did Mrs Robinson buy

4 When was your father in Nghe An

5 How do they go to school

6 Why didn't she go to class

7 Who left home at 7o'clock yesterday

8 What subject does he study in the high school

9 What is your favorite hobby

10 How far is it

Trích mẫu thử

Sục khí $CO_2$ tới dư vào mẫu thử : 

- mẫu thử tạo kết tủa trắng là $Ba(OH)_2$
$Ba(OH)_2 + CO_2 \to BaCO_3 + H_2O$

- mẫu thử không hiện tượng gì là $NaCl$

Bài 13:

$6-2\sqrt{5}=5-2\sqrt{5}.\sqrt{1}+1$

$=(\sqrt{5}-1)^2$

Tương tự: $6+2\sqrt{5}=(\sqrt{5}+1)^2$
Do đó:
$M=\sqrt{(\sqrt{5}+1)^2}-\sqrt{(\sqrt{5}-1)^2}$

$=|\sqrt{5}+1|-|\sqrt{5}-1|=(\sqrt{5}+1)-(\sqrt{5}-1)$

$=2$

Bài 14:

a.

$M=\sqrt{4+2\sqrt{4}.\sqrt{5}+5}-\sqrt{4-2\sqrt{4}.\sqrt{5}+5}$

$=\sqrt{(\sqrt{4}+\sqrt{5})^2}-\sqrt{(\sqrt{4}-\sqrt{5})^2}$

$=|\sqrt{4}+\sqrt{5}|-|\sqrt{4}-\sqrt{5}|$

$=2+\sqrt{5}-(\sqrt{5}-2)=4$

b.

$N=\sqrt{7-2\sqrt{7}+1}-\sqrt{7+2\sqrt{7}+1}$

$=\sqrt{(\sqrt{7}-1)^2}-\sqrt{(\sqrt{7}+1)^2}$

$=|\sqrt{7}-1|-|\sqrt{7}+1|$

$=(\sqrt{7}-1)-(\sqrt{7}+1)=-2$

Bài 15:

a.

$P=\sqrt{3^2+2.3\sqrt{2}+2}-\sqrt{3^2-2.3\sqrt{2}+2}$

$=\sqrt{(3+\sqrt{2})^2}-\sqrt{(3-\sqrt{2})^2}$

$=|3+\sqrt{2}|-|3-\sqrt{2}|$

$=3+\sqrt{2}-(3-\sqrt{2})=2\sqrt{2}$

b,

$Q=\sqrt{9+2\sqrt{9.8}+8}+\sqrt{9-2\sqrt{9.8}+8}$

$=\sqrt{(\sqrt{9}+\sqrt{8})^2}+\sqrt{(\sqrt{9}-\sqrt{8})^2}$

$=|3+\sqrt{8}|+|3-\sqrt{8}|$

$=3+\sqrt{8}+(3-\sqrt{8})=6$

ko có ảnh bn ơi

Đề bài là gì zạ? 

1 Ann is very upset because the local authorities have turned down her proposals to install solar panels to supply electricity for traffic lights

2 A committe has been set up to examine the question

3 Our class football team lost the match, so we tried to cheer them up

4 "Can I wear jeans at wedding party?" - "Of course not. You'll have to cover up smart clothes"

Ann is very upset because the local authorities have turned down her proposals to install solar panels to supply electricity for traffic lights

A committe has been set up to examine the question

Our class football team lost the match, so we tried to spirit them up /cheer them up

"Can I wear jeans at wedding party?" - "Of course not. You'll have to cover up smart clothes"

Before I come to a decision, I'll have to think over their offer very carefully

1.Ann is very upset because the local authorities have turned down her proposals to install solar panels to supply electricity for traffic lights.

2.A committe has been set up to examine the question.

3.Our class football team lost the match, so we tried to cheer them up,

4.''Can I wear jeans at wedding party?'' - ''Of course not.You'll have to cover up smart clthes''

5.Before I come to a decision, I'll have to think over their offer very carefully.