1. They feed the dogs and cats every day

=> The dogs and cats are fed every day.

2. Students must do their homework before days

=> Their homework must be done by students before days.

3. They are decorating the Christmas tree now

=> The Christmas tree is being decorated now.

4. He has just sent me a greeting card on my birthday

=> I have just been sent a greeting card on mu birthday.

5. Mary cooks the meals every day

=> The meals are cooked by Mary every day.

6. People usually use computer to design new models

=> Computer is usually used to design new models.

7. Mr.Brown has typed his assignment for 2 hours

=> His assignment has been typed by Mr.Brown for 2 hours.

8. My mother is cleaning the rooms right now

=> The rooms are being cleaned by my mother right now.

9. In which coutries do they speak E?

=> Is English spoken in which coutries?

10. Tom is doing his homework in his room now

=> His homework is being done in his room by Tom now.

1.They used to..go..swimming in the morning (go)

2.He wishes he ...were...a doctor (be)

3.I wish they.would be...here tomorrow (be)

4.We wish it ..wouldn't rain..(not rain)

5. Lan and Maryan..have been..pen pals for over two years (be)

6.Jeans....are sold....all over the world (sell)

7. English ....is spoken....in many countries in the world (speak)

8.This test should....be written....in English(write)

9.We..have learnt....English since 2006 (learn)

\(\left(2x-1\right)^2-\left(4x+1\right)\left(x-3\right)=-3\)

\(\Leftrightarrow4x^2-4x+1-4x^2+12x-x+3=-3\)

\(\Leftrightarrow7x=-3-1-3=-7\Leftrightarrow x=-1\)

Ta có:

\(P\left(0\right)=a.0^2+b.0+c=-2\Rightarrow c=-2\)

\(4P\left(x\right)-P\left(2x-1\right)=6x-6\)

\(\Leftrightarrow4\left(ax^2+bx+c\right)-a\left(2x-1\right)^2-b\left(2x-1\right)-c=6x-6\)

\(\Leftrightarrow4ax^2+4bx+4c-a\left(4x^2-4x+1\right)-2bx+b-c=6x-6\)

\(\Leftrightarrow2bx-8+4ax-a+b+2=6x-6\)(Do c=-2)

\(\Leftrightarrow x\left(2b+4a\right)-\left(a-b+6\right)=6x-6\)

Do thỏa mãn với mọi x nên:

\(\left\{{}\begin{matrix}2b+4a=6\\a-b+6=6\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}b+2a=3\\a-b=0\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}a=1\\b=1\end{matrix}\right.\)

Ta có :

\(\left\{{}\begin{matrix}a=1\\b=1\\c=-2\end{matrix}\right.\Leftrightarrow a+b+c=0\)

=> \(P\left(x\right)=x^2+x-2\)

a)

- Số số có 1 chữ số là: \(9-5+1=5\left(số\right)\Rightarrow\) Có 5 chữ số.

- Số số có 2 chữ số là: \(90-10+1=81\left(số\right)\Rightarrow\) Có \(81.2=162\) (chữ số)

=> B có: \(5+162=167\)(chữ số)

b)

Ở hàng đơn vị chữ số 2 xuất hiện: 8 lần. (12;22;...;82)

Ở hàng chục chữ số 2 xuất hiện 10 lần. (20;21;22;...;29)

=> Không tính lần lặp lại thì có 18 số. Nhưng có số 22 lặp nên chỉ còn 17 lần xuất hiện chữ số 2.

c) Trong 50 chữ số đầu có 5 số có 1 chữ số => Chỉ có 45 số có 2 chữ số.

Ta thấy: \(45:2=22\)(dư 1)

=> Số đứng thứ 22 của số có 2 chữ số là: \(22-1+10=31\)

Đồng nghĩa với việc số đứng thứ 49 là 1=> số đứng thứ 50 của dãy là 3.(31=>32)

d)

Số 1 xuất hiện: 10+8-1=17(lần)

Số 2 xuất hiện 17 lần.

Số 3 xuất hiện 17 lần.

Số 4 xuất hiện 17 lần.

Số 5 xuất hiện 18 lần (thêm chữ số 5 nữa)

Số 6 xuất hiện 18 lần.

Số 7 xuất hiện 18 lần.

Số 8 xuất hiện 18 lần.

Số 9 xuất hiện 10 lần.

=> tổng các chữ số của B là: 17(1+2+3+4)+18(5+6+7+8)+9.10=728

cạch khu đất hình vuông đó là:

1 : 4 = 0.25 km

vậy diện tích khu đất đó là:

0,25 x 0,25 =0,0625 km2=6,25ha

Đ/S:6,25 ha

c) 2,3,5,7,8 nhé

Nếu thành phần giống mình gạch chân thì đây luôn nhé:

1. It is ten past eleven . ==> What time is it?

2. She is in class 6B. ==> What class is she in?
3. They have two children. ==> How many childten do they have?
4. Lan ‘s classroom is on the first floor . ==> Where is Lan's classroom?
5. She has lunch at eleven thirty. ==> When does she have lunch?
6. There is one clock in the living room . ==> How many clocks are there in the living room?
7. Mr Quang lives in the country. ==> Where does Mr.Quang live?

Answer these questions using reflexice pronouns

1.Who cut your hair for you?

Nobody,I cut it...myself....

2.Who told you Alice was getting married?

Alice.....told me herself.....

3.Does Mr.John have a secretary to type his letters?

No,he ... types them himself..

4,Do you want me to post that letter for you?

No,I'll...do it myself.....

5,Can you clean the windows for me ?

Why don't you....clean them yourself?.....

1.The boy was lucky when he fell down the stairs.He didn't ...hurt himself...

2.I'm trying to ...teach myself..... Spanish but I'm not making much progress

3.He spends most of his time alone so it's not surprising that he ....talks to himself......

4.Don't worry about us.We can .....look after ourselves.....

5.I'm not going to do it for you.You can ..... do it yourself.......