refer

1. “Open the door,” he said to them.
-He told them to open the door.
2. “Where are you going?” he asked her.
-He asked her where she was going
3. “Which way did they go?” he asked.
-He asked which way they had gone
4. “Bring it back if it doesn’t fit”, I said to her.
-I told her to Bring it back if it didnt fit
5. “Don’t try to open it now,” she said to us.
-She told us to not try to open it then
6. “Is it going to be a fine day today?” I asked her.
-I asked her if it was going to be a fine day that day
7. “He’s not at home”, she said.
-She said that he was not at home
8. “Is the bus station far away?” the girl asked.
-The girl wanted to know if the bus station was far away
9. “Don’t stay late Ann” Tom said.
-Tom told Ann not to stay late
10. “Please let me borrow your car,” he said to her.
-He asked het to let him borow her car
11. “Jean, have you seen my gloves?” Thomas asked.
-Thomas asked Jean if he had seen his gloves
12. Don’t leave the window open, Mary”, I said.
-I told Mary not to leave the window open
13. “I’ll have a cup of tea with you,” she said.
She said that she would have a cup of tea with me
14. “I’ll pay him if I can” she said.
-She said that she would pay him if she could
15. “What are you going to do next summer?” she asked.
- She asked us what we were you going to do the next summer

Bài `13`

\(a,\sqrt{27}+\sqrt{48}-\sqrt{108}-\sqrt{12}\\ =\sqrt{9\cdot3}+\sqrt{16\cdot3}-\sqrt{36\cdot3}-\sqrt{4\cdot3}\\ =3\sqrt{3}+4\sqrt{3}-6\sqrt{3}-2\sqrt{3}\\ =\left(3+4-6-2\right)\sqrt{3}\\ =-\sqrt{3}\\ b,\left(\sqrt{28}+\sqrt{12}-\sqrt{7}\right)\cdot\sqrt{7}+\sqrt{84}\\ =\left(\sqrt{4\cdot7}+\sqrt{4\cdot3}-\sqrt{7}\right)\cdot\sqrt{7}+\sqrt{4\cdot21}\\ =\left(2\sqrt{7}+2\sqrt{3}-\sqrt{7}\right)\cdot\sqrt{7}+2\sqrt{21}\\ =2\cdot7+2\sqrt{21}-7+2\sqrt{21}\\ =14+2\sqrt{21}-7+2\sqrt{21}\\ =7+4\sqrt{21}\)

17:
ĐKXĐ: \(\left\{{}\begin{matrix}x>=0\\x< >4\end{matrix}\right.\)

Để A là số nguyên thì \(\sqrt{x}-1⋮\sqrt{x}-2\)

=>\(\sqrt{x}-2+1⋮\sqrt{x}-2\)

=>\(\sqrt{x}-2\in\left\{1;-1\right\}\)

=>\(\sqrt{x}\in\left\{3;1\right\}\)

=>\(x\in\left\{9;1\right\}\)

16:

a: BC=BH+CH

=9+16

=25(cm)

Xét ΔABC vuông tại A có AH là đường cao

nên \(AH^2=HB\cdot HC\)

=>\(AH=\sqrt{9\cdot16}=12\left(cm\right)\)

Xét ΔABC vuông tại A có AH là đường cao

nên \(\left\{{}\begin{matrix}AB^2=BH\cdot BC\\AC^2=CH\cdot BC\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}AB=\sqrt{9\cdot25}=15\left(cm\right)\\AC=\sqrt{16\cdot25}=20\left(cm\right)\end{matrix}\right.\)

b: M là trung điểm của AC

=>AM=AC/2=10(cm)

Xét ΔAMB vuông tại A có

\(tanAMB=\dfrac{AB}{AM}=\dfrac{15}{10}=\dfrac{3}{2}\)

nên \(\widehat{AMB}\simeq56^0\)

Em xin anh chị làm giùm em với 😥😥😥

bài 5:
25,5kg hết số tiền là:
(60 000:5)x25,5=306 000(đồng)
Đ/S: ...
bài 6: 
3,5 giờ đi được số km là:
(200:5)x3,5=140(km)
Đ/S: ...
bài 7:
chiều rộng là:
18,2:2=9,1(m)
chu vi là:
(18,2+9,1)x2=54,6(m)
diện tích là:
18,2x9,1=165,62(m²)
Đ/S: ...

Bài 5

1kg gạo cần số tiền là :

60.000 : 5 = 12.000 (đồng)

25,5kg gạo hết số tiền là :

12.000 nhân 25,5 = 306.000 (đồng)

Bài 6

1h đi đc số km là :

200 : 5 = 40 (km)

3,5 h đi đc số km là :

40 nhân 3,5 = 140(km)

Bài 7

Chiều rộng hcn là : 18,2 nhân 1/2 =9,1(m)

Chu vi hcn là :

(18,2 +9,1) nhân 2 = 54,6 (m)

Diện tích hcn là :

18,2 nhân 9,1 = 165,62 (m2)

Những chỗ có more, er: so sánh hơn vì có 2 đối tượng so sánh

Những chỗ có most: so sánh nhất vì đó là đối tượng tốt nhất trong nhiều đối tượng được so sánh

1. more expensive than 

2. better than

3. more convinient than

4. the most expensive

5. the longest

6. the most interesting

7. the best

8. the most beautifully

9. the coldest

10. the most important

giúp em với

cái này dùng phân số trung gian thôi

-313/370 < -313/371 < -314/371

nên -313/370 < -314/371

các câu sau tương tự

cảm ơn

Đây bn nhé:

Ta có a/3 = b/8= c/5. Áp dụng tính chất dãy tỉ số bằng nhau ta có:

2a+3b-c/2.3+3.8-5 = 2a+3b-c/6+24-5 = 50/25 = 2

=> a/3 = 2 => a=6

=> b/8 = 2 => b=16

=> c/5 = 2 => c=10

Nhìn ngắn vậy thôi chứ ko sai đâu bn

Chúc bn học tốt^^

  \(\dfrac{a}{3}\) = \(\dfrac{b}{8}\) = \(\dfrac{c}{5}\) và 2a + 3b - c = 50

=> \(\dfrac{2a}{6}\) = \(\dfrac{3b}{24}\) = \(\dfrac{c}{5}\) và 2a + 3b - c = 50

  Áp dụng tính chất dãy tỉ số bằng nhau ta có:

      \(\dfrac{2a}{6}\) = \(\dfrac{3b}{24}\) = \(\dfrac{c}{5}\) = \(\dfrac{2a+3b-c}{6+24-5}\) = \(\dfrac{50}{25}\) = 2

  Vậy:

       \(\dfrac{2a}{6}=2\)  => \(2a=2.6=12\)  => \(a=12:2=6\)

       \(\dfrac{3b}{24}=2\)  => \(3b=2.24=48\) => \(b=48:3=16\)

       \(\dfrac{c}{5}=2\)  => \(c=2.5=10\)