ĐẶt ƯCLN(20n+9 ; 30n+13) = d

\(\Rightarrow\left(20n+9\right)-\left(30n+13\right)⋮d\)

\(\Rightarrow3\left(20n+9\right)-2\left(30n+3\right)⋮d\)

\(\Rightarrow\left(60n+27\right)-\left(60n+26\right)⋮d\)

\(\Rightarrow1⋮d\)

\(\Rightarrow d=1\)

\(\RightarrowƯCLN\left(20n+9;30n+13\right)=1\) (đpcm)

Vì khi bớt đi 2,1 rồi thêm 4,5 và 29 thì ta có:

29-4,5+2,1=26,6

Vậy số đó là 26,6

Bài này phải tính theo phương pháp làm ngược lại ,mình giải cho bạn rồi đó,tick mình với nha cảm ơn bạn nhiều,xin lỗi vì không kết bạn với bạn được

Mỗi l dầu nặng số kg là:

3,42:4,5=0,76(kg)

8 l dầu nặng số kg là:

0,76 x 8=6,08 (kg)

tick với nha câu hỏi của bạn sai đề không phải là KI-LÔ-MÉT VẢI mà là KG 

đè sai??

1.What are your favorite activities for the summer vacation?

My favourite activities for the summer vacation is travelling

2.How do you often spend your free time?

I spend my free time on surfing the internet

3.How much time do you spend doing your homework in the evening?

I spend for about 4 hours

4.Which do you prefer doing at weekends,staying at home or going out?

I prefer staying at home to going out

5.Do you like traveling?What is your favorite place of interest?

Yes, I do. It's the US

7.What cities have you visited?Which one do you like most?

I visited Ha Noi, HCM City, Nha Trang,... I like HCM City most

8.Do you like taveling by bus?Why(not)?

No, I don't. Because I have carsick

9.Where do people in your neighborhoos often go shopping?

Supermarket

Complete each blank in the sentences with only ONE suitable world.

26. I' ve eaten too many sweets. I have toothache

27. Do you have a painkiller? I have a few

28. I have stomachache.I think that food was bad.

29. I have a pain in my leg.

30. Ouch! My arm hurts

31. I got some water in my ear and now i have flu.

32. I can't eat any biscuits.I have a sore throat

33. That's a bad cold.Try some hot lemon tea.

34. When you have flu , you usually have a high pressure

35. He ate some seafood yesterday. Now he doesn't feed well.He thinks he has a/ an stomachache

Chọn từ nhấn vần first :

1. A. Photo

B. Invite

C. Between

D. Bamboo

2. A. Enjoyable

B. Village

C. Arrive

D. Exchang

3. A. Complete

B. Member

C. Hamburger

D. Collect

4. A. Together

B. Relax

C. Vietnamese

D. Moutain

Sắp xếp:

7, next / they / show / around / them / week / Hanoi / Hoa / visit / will / when / her.

Hoa will show them around Hanoi when they visit her next week
8, every / early / to / morning / Hoa / take / gets / exercises / day / up.

Hoa gets up early to take exercises every morning
9, the / not / teeth / dentist / her / her / worry / told / looked / and / at / to.

The dentist looked at her teeth and told her not to worry

change the following statements into reported speeh

1.My father is in hospital.=>jim said his father was in hospital

2.Nora and Jim are getting married next month.=>She said Nora and Jim were getting married the next month

3.I haven't seen Bill for a while.=>Tim said he hadn't seen BIll for a while

4.I've been playing tennis a lot recently.=>my father said he had been playing tennis a lot recently

5.Margaret has had a baby.=>she said margaret had had a baby

6.I don't know what Fred is doing.=>George said he didn’t know what Fred was doing

7.I hardly ever go out these days.=>he said he hardly ever went out those days

8.I work 14 hours a day.=>lan'brother said he worked 14 hours a day

9.I'll tel Jim I saw you.=>he said he would tell Jim he had seen me

10.you can come and stay with me if you are in london=>Bill said I could come and stay with him if I was in London

11.Tom had an accident last week but he wasn't injured.=>Joe said Tom had had an accident the previous week but he hadn’t been injured

12.I saw Jack at a party a few months ago and he seemed fine.=>Jone said he had seen Jack at a party a few months ago and he had seemed fine

13.I can't come to the party on Friday.=>binh said he couldn't come to the party on Friday

14.I want to go on holiday but I don't know where to go=>the girl said she wanted to go on holiday but she didn''t know where to go

15.We have a lift but very often it doesn't work.=>they said they had a lift but very often it didn't work

16.It isn't so rainy today as it was yesterday=>he remarked it wasn't so rainy today that day as it had been the previous day

17.the sun rises in the east and sets in the west.=>the teacher said that

the sun rose in the east and set in the west

I. fill in the blank with suitable form of verbs:

a, He hopes ....to pass.../pass/ his next exam.

b, He suggested.....holding..... /hotd/ another meeting.

c, You'll have to wait until the stops...talking.../talk/.

d, I try ...not to make..../ not make/ the same mistake again.

e, Would you like...to have.../have/ the next dance with me ?

g, He's expecting....to make..../make/ a trip to HLB.

h, Does the city government intend ....to do... /do/ anything about pollution ?