\(9,=\dfrac{\sqrt{5}+1-\sqrt{5}+1}{\left(\sqrt{5}-1\right)\left(\sqrt{5}+1\right)}=\dfrac{2}{4}=\dfrac{1}{2}\\ 10,=\dfrac{\sqrt{5}+2+\sqrt{5}-2}{\left(\sqrt{5}-2\right)\left(\sqrt{5}+2\right)}=2\sqrt{5}\\ 11,=\dfrac{8+6\sqrt{2}-8+6\sqrt{2}}{\left(4-3\sqrt{2}\right)\left(4+3\sqrt{2}\right)}=\dfrac{12\sqrt{2}}{-2}=-6\sqrt{2}\\ 12,=\dfrac{2+\sqrt{6}+2-\sqrt{6}}{\left(2-\sqrt{6}\right)\left(2+\sqrt{6}\right)}=\dfrac{4}{-2}=-2\\ 13,=\sqrt{2}-1+\sqrt{2}+3=2\sqrt{2}+2\\ 14,=2-\sqrt{3}+\sqrt{3}-1=1\\ 15,=3-\sqrt{5}+\sqrt{5}-2=1\)

1/

1. although

2. around

3. where

4. forward

5. and

6. will

2/ 1B 2F 3E 4A 5D 6C

3/

1. daily

2. wearing

3. would do

4. haven't eaten

5. is being carried

6. rises

7. inexperienced

8. equality

4/

1. which -> who

2. pollute -> polluting

5/

1. not to touch that

2. Tom has met is

3. weren't ill

4. may be built

6/

1. environmentalists

2. affect

3. media

4. responsible

7/

1. T

2. T

3. F

4. F

Part 6 

1/ students

2/affect

3/media

4/make

mở bài là giới thiệu về cụ nha mn em viết lộn ạ 

thân bài là đóng góp ạ 

khoanh toàn C

1 A

2 D

3 C

4 A

5 C

6 câu này sai 2 chỗ A và C

7 A

8 B

9 B

1 A

2 D

3 C

4 A

5 C

6 A

7 A

8 B

thi thì tự làm nha

I.
1. A
2. D
II.
3. D 
4. B
5. D
6. C
7. C
8. A
9. C
10. B

CHÚC BẠN HỌC TỐT!

Viết lại câu:

6 A

7 A

8 D

9 B

10 C

11 D 

12 A

13 B

14 D

15 A

Lỗi sai

1 C => which

2 C => stopped

3 A => bored

4 B => most

5 B => had stopped

6 C => that

7 C => had knowm

8 A => hadn't been

9 D => learned about

10 B => bỏ

11 B => have come

12 A => would have gone

13 C => would have returned

14 C => knew

6.a

7.a

8.d

9.b

10.c

11.d

12.a

13.b

14.d

15.a

Bài chọn lỗi sai

1.c =>which

2.c => stopped

3.a =>bored

4.b => most

5.b =>had stopped

6.c =>that

7.c => had known

8.a => hadn't been late

9.d => learned about

10.b => rỗng

11.b => would have come

12.a => would have gone

13.c => would have returned

14.c => knew

Bài 3:

1, Áp dụng t/c dtsbn:

\(\dfrac{x}{6}=\dfrac{y}{4}=\dfrac{z}{3}=\dfrac{z-x}{3-6}=\dfrac{-21}{-3}=7\\ \Rightarrow\left\{{}\begin{matrix}x=42\\y=28\\z=21\end{matrix}\right.\)

2, Áp dụng t/c dtsbn:

\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{7}=\dfrac{2x+3y-z}{6+15-7}=\dfrac{-14}{14}=-1\\ \Rightarrow\left\{{}\begin{matrix}x=-3\\y=-5\\z=-7\end{matrix}\right.\)

Bài 4: 

Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:

\(\dfrac{x}{\dfrac{1}{2}}=\dfrac{y}{\dfrac{1}{3}}=\dfrac{z}{\dfrac{1}{4}}=\dfrac{x+y+z}{\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}}=\dfrac{130}{\dfrac{13}{12}}=120\)

Do đó: x=60; y=40; z=30

giúp mk bài 4 với ạ

\(\left|3x+2\right|=\left|4x-3\right|\)

\(\Leftrightarrow\left[{}\begin{matrix}3x+2=4x-3\\3x+2=3-4x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}-x=-5\\7x=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{1}{7}\end{matrix}\right.\)

\(\left|2+3x\right|=\left|4x-3\right|\)

\(\Leftrightarrow\left[{}\begin{matrix}2+3x=4x-3\\2+3x=3-4x\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{1}{7}\end{matrix}\right.\)