1. Tìm số mol HCl có trong 0.25 lts HCl , 0.2M

2.Tìm khối lượng chất tan có trong 50ml NaOH , 0.1M

Chuyển câu trực tiếp thành gián tiếp

16 Ann said, 'Englishmen make good husbands because they are nearly always willing to help in the house.'

17 Mary answered, 'I like men to be useful but I don't like them to be too domesticated. I prefer them to keep out of the kitchen altogether. Men look silly in aprons anyway.'

18 Motoring report: The new Rolls Royce runs so quietly that all you can hear is the ticking of the clock. Managing director of the Rolls Royce company: In that case we'll have to do something about the clock.

19 'I don't know what to do with all my plums. I suppose I'll have to make jam. The trouble is that none of us eats jam,' she said.

20 'We like working on Sundays because we get double pay,' explained the builders.

21 He said, 'I am quite a good cook and I do all my own washing and mending too.'

22 'You can keep that one if you like, Joan,' he said. 'I've got plenty of others.'

23 'I'm going fishing with mother this afternoon,' said the small boy, 'and we are going into the garden now to dig for worms.' (Omit now).

24 'You've got my umbrella,' I said crossly. 'Yours is in your bedroom.'

25 'I know exactly what they said,' the private detective explained to his client, 'because I bugged their phone.' 

26'I'll sit up till she comes in, but I hope she won't be late,' he said.

27 'If you give me some wire, I'll hang that picture for you,' said my cousin. 

28'I have a Turkish bath occasionally, but it doesn't seem to make any difference to my weight,' she said

29 'This is quite a good model, madam. I use one of these myself,' said the salesman.

30 'My new house is supposed to be haunted, but so far I haven't seen any ghosts,' she said.

31 The advertisement said, 'If you answer the questions correctly you may win £100.'

32 'If I press my ear against the wall, I can hear what the people in the next flat are saying,' he said.

Cho \(a,b,c>0\) thỏa mãn \(ab+bc+ca=3\) . CMR : \(\sqrt[3]{\dfrac{a}{b\left(b+2c\right)}}+\sqrt[3]{\dfrac{b}{c\left(c+2a\right)}}+\sqrt[3]{\dfrac{c}{a\left(a+2b\right)}\ge\dfrac{3}{\sqrt[3]{3}}}\)

Lớp 8 chưa học giải toán bằng hệ phương trình mà cô ?

Em nghĩ lời giải sau phù hợp hơn ạ :

Nửa chu vi HCN là : 54:2=27(cm)

Gọi chiều dài của HCN ban đầu là a (m)( a>13.5)

Theo bài ra ta có :

(a-1)(27-a+2)-a(27-a)=22

=>a=17

Chiều rộng ban đầu là : 27-17=10 (m)