Câu 3: 

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

\(\dfrac{x}{3}=\dfrac{y}{2}=\dfrac{x+y}{3+2}=\dfrac{90}{5}=18\)

Do đó: x=54; y=36

các anh chiến sĩ thật gan dạ, quả cảm và đầy tình yêu thương.

1 từ: dũng cảm

1 câu: Những anh bộ đội trong bức ảnh đã không ngại gian khổ, dũng cảm vào dòng nước lũ để giúp đỡ người dân.

\(21,B\\ 22,B\\ 23,C\\ 24,A\\ 25,B\\ 16,C\\ 17,C\\ 18,D\\ 19,B\\ 20,A\)

Hóa bạn qua bên box Hóa đăng nhé

Bài 1:

a. \(p=dh=10300\cdot36=370800\left(N/m^2\right)\)

b. \(160cm^2=0,016m^2\)

\(p=\dfrac{F}{S}\Rightarrow F=S\cdot p=0,016\cdot370800=5932,8\left(N\right)\)

Bài 2:

Ta có: \(p_2>p_1\left(1165000>875000\right)\)

\(\Rightarrow\) Tàu đăng lặn xuống, vì khi càng xuống áp suất lại càng tăng.

\(\left\{{}\begin{matrix}p'=dh'\Rightarrow h'=\dfrac{p'}{d}=\dfrac{875000}{10300}\approx84,9\left(m\right)\\p''=dh''\Rightarrow h''=\dfrac{p''}{d}=\dfrac{1165000}{10300}\approx113\left(m\right)\end{matrix}\right.\)

Bài 3:

\(20cm=0,2m\)

\(p=dh=8000\cdot\left(1,8-0,2\right)=12800\left(N/m^2\right)\)

Bài 4:

\(p=dh=10000\cdot2,8=28000\left(N/m^2\right)\)

\(150cm^2=0,015m^2\)

\(p=\dfrac{F}{S}\Rightarrow F=S\cdot p=0,015\cdot28000=420\left(N\right)\)

Bạn cần bài nào ạ? Nếu cần tất cả các bài trên thì bạn tách ra từng CH khác nhau nhé, đăng vào 1 câu tỉ lệ giúp sẽ ít, chất lượng làm bài không được cao.

1 Should Jane be helped with the sewing?

2 Judy's car is being repaired by the mechanic

3 A computer is used to do that job nowadays

4 All travel expenses must be paid for this training course by employers

5 Were they taken in by her story?

10 Beer used to be drunk for breakfast in England years ago

11 The letter might have been sent to the wrong address

12 The hole on the wrong side of the road is being digged

13 Your money is going to be stolen if you are not careful

14 Have you ever been asked for your opinion?

15 I am not impressed by Alan's knowledge

16 How are candles made?

17 When are the results of the contest announced?

18 The police weren't informed that there had been a mistake

19 Where will you be sent by your company next year?

20 By whom were the children looked after when you were away?

21 Look! The seals are being fed

22 The book had been returned to the library by Kathy

23 By this time tomorrow, The announcement will have been made by the president

24 People's breathing was being affected by the pollution in the city

25 Those papers haven't been signed by Mrs Andrews yet. Have them been signed by Mr Andrews yet?

26 Is that airplane flown by a student

27 Where was the 1988 Olympic Games held?

28 Are those tractors made, or are they imported?