CHiều dài đáy là : \(\frac{20}{4}=5m\)

Diện tích xung quanh là : \(3\times2\times\left(4+5\right)=54m^2\)

Diện tích toàn phần là : \(54+20\times2=94m^2\)

Chiều dài của cái thùng dạng hình hộp chữ nhật là :

                70 : 4 = 17,5 ( dm )

Diện tích xung quanh của cái thùng dạng hình hộp chữ nhật là :

           ( 17,5 + 4 ) x 2 x 3,5 = 150,5 ( dm² )

Diện tích toàn phần của cái thùng dạng hình hộp chữ nhật là :

              150,5 + ( 70 x 2 ) = 290,5  ( dm² )

                                Đáp số : 290,5 dm²

2. What kind of board games do you like? 3. What do you think of Take That? 4. Who's your favourite singer? 5. What's your favourite computer game? 6. Are you interested in fashion? 7. Do you prefer reading or drawing?

khong lam duoc ?

\(P=\frac{x^2}{x-2}=\frac{x^2-4x+4+4x-4}{x-2}=\frac{\left(x-2\right)^2+4\left(x-2\right)+4}{x-2}=x-2+4+\frac{4}{x-2}\)

\(\ge2\sqrt{\left(x-2\right).\frac{4}{x-2}}=4+4=8\)

Dấu \(=\)xảy ra khi \(x-2=\frac{4}{x-2}\Leftrightarrow\left(x-2\right)^2=4\Leftrightarrow x=4\)(vì \(x>2\)).

ta có : 

\(\frac{x^2-3x+12}{x-1}=x-2+\frac{10}{x-1}=x-1+\frac{10}{x-1}-1\)

Ta cần điều kiện \(x-1>0\) thì biểu thức mới tồn tại giá trị nhỏ nhất. khi đó

áp dụng bất đẳng thức Cauchy ta có \(x-1+\frac{10}{x-1}-1\ge2\sqrt{10}-1\)

bạn ơi, làm gì vậy bạn ?

mình đang học

a, Ta có : \(A=\frac{2}{3}x^3y.\frac{3}{4}xy^2z^2=\frac{1}{2}x^4y^3z^2\)

b, Bậc : 4 

c, hệ số : 1/2 ; biến x^4y^3z^2 

d, Thay x = -1 ; y = -2 ; z = -3 vào đơn thức trên ta được 

\(A=\frac{1}{2}.1.\left(-8\right).9=-36\)

Question 1. He ..... a doctor.

A. was

B. were

Question 2. Water

A. Countable nouns

B. Uncountable nouns

Question 3. ......... you student

A. am

B. is

C. are

Question 4. She ...... a teacher.

A. were

B. was

Question 5. He/She/It .....

A. am

B. is

C. are

Question 6. I ...

A. am

B. is

C. are

Question 7. We/You/They ....

A. am

B. is

C. are

Question 8. I/He/She/It .....

A. was

B. were

Question 9. We/You/They .....

A. was

B. were

Question 10. Ben is in the hospital.

He is a ......

A. berre

B. sherry

C. doctor

Question 11. The students and teacher is in the school

Ben is a ........

A. student

B. teacher

Mary is a .......

A. teacher         hai câu này đều chọn được nhé!

B student

Thu gọn

Bài này trả lờ từng câu nhé.+

Trời cao và trong xanh.

Nếu cô cậu bảo đặt câu hỏi cho câu này thì đây:

Trời như thế nào?

I. Put the verbs in the correct tenses

1. I often (wash) wash my clothes.

2. She (not be) isn't at home

3. .Do.You often (write) ....write.......to your friend?

4. Mr.Mai (water) ...waters.... the plant evey morning.

5. We (meet) ...meet....... each other twice a month.

6. He (listen) ..is listening.. to the telephone at the moment.

7. They always (not go) ..don't always go...to the school by train.

8. He (drink) ..is drinking.. beer at the bar

9. They usually (sing) .sing.. in the early morning.

10. Mi and Thanh (talk) ......Are Mi and Thanh talking......... on the telephone now?

11. They (plant) ..plant.......trees in the early year.

12. He (not study)..isn't studying... Math at the moment.

13. She (play) ..Does she play.. badminton every afternoon?

14. They sometimes (do) .....do......... morning exersices at 5.30.

15. Thanh and I (be) .....are...... at home now.

16. Hung (run) ....runs...... about 5 km every morning.

17.Do  Hung and Minh sometimes (meet) .....meet.....each other?

18. Every evening, she (jog) …jogs…about 3 km.

19.......Is.he.........................your father?

20. He always (drive) ..drives..his car to work. But now, he (ride) ...is riding... his motorbike to work. 

II. Complete the sentences with the correct form of the verb in brackets.

1.      Which sports do you (play) play at the weekends?

2.      My brother (buy) .…bought. 2 tickets for the table tennis match yesterday.

3.      Last weekend I (play) played with my friends and we (have). a very good time.

4.      Nowadays many girls (like/do) like doing aerobics to keep fit.

5.      What time do you (arrive)…arrive…….. at the stadium?

6.      How often does he (go/fish) go fishing?

7. Did your team (win) win yesterday?

8.      My sister (play). ……plays……..     badminton twice a week. She (do) does it on Saturday and Sunday.

9.      Where did you (go) go on holiday last year?

10.     I (cycle)………cycled………   100 kilometers last week