1.Yes, they do

2..Yes, it is

3.People buy fruits and flowers from the market and decorate their house

4.People visit their family and friends

1, That
2, This
3, that
4, those
5, these - that
6, these
7, this
8, that
9, that
10, this
11, those
12, this
13, it
14, these
15, them

16, those

this/that dùng cho ng, vật số ít

this: dùng cho ng, vật ở gần

that: dùng cho ng, vật ở xa

these/those dùng cho ng, vật số nhiều

these: ở gần

those: ở xa

1. this

2. This

3. that

4. those

5. these/ that

6. these

7. This

8. that

9. that

10. this

11. those

12. this

13. it

14. these

15. them

16. those

1 friendly

 2 creative

3 boring

4 funny

5 sensitive

6  outgoing

7 lazy

8 impatient

9 active

10 quiet

Lời giải:
Đặt $xy=k$. Ta có:

$x_1y_1=k=x_2y_2$

Thay $x_1=6; x_2=-9\Rightarrow 6y_1=-9y_2$

$\Leftrightarrow y_1=-1,5y_2$

$y_1-y_2=10$

$-1,5y_2-y_2=10$

$-2,5y_2=10$

$y_2=-4$

$y_1=-1,5y_2=-1,5.(-4)=6$

\(11,\\ a,M=\dfrac{1+\sqrt{a}}{\sqrt{a}\left(\sqrt{a}-1\right)}\cdot\dfrac{\left(\sqrt{a}-1\right)^2}{\sqrt{a}+1}=\dfrac{\sqrt{a}-1}{\sqrt{a}}\\ b,M=\dfrac{\sqrt{a}-1}{\sqrt{a}}=1-\dfrac{1}{\sqrt{a}}< 1\left(\dfrac{1}{\sqrt{a}}>0\right)\)

\(9,\\ a,=\left|2-\sqrt{7}\right|=\sqrt{7}-2\\ b,=5\sqrt{3}+4\sqrt{3}-10\sqrt{3}=-\sqrt{3}\\ c,=3-4+2=1\\ d,=6\sqrt{3a}-4\sqrt{3a}=2\sqrt{3a}\\ 10,\)

a, Áp dụng HTL: \(x=\sqrt{9\cdot25}=15\)

b, Áp dụng HTL: \(\left\{{}\begin{matrix}8^2=10x\\y^2=x\left(x+10\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=6,4\\y=\sqrt{6,4\cdot16,4}\approx10,245\end{matrix}\right.\)