có 6 túi loại 4 kg

có 7 túi loại 2,5 kg

A =  2 + 2² + 2³ + 2⁴ + ... + 2⁵⁸ + 2⁵⁹ + 2⁶⁰

A = (2 + 2² + 2³ + 2⁴) + ... + (2⁵⁷ +  2⁵⁸ + 2⁵⁹ + 2⁶⁰)

A = (2.1 + 2.2 + 2.2.2 + 2.2.2.2) + ... + (2⁵⁷.1 +  2⁵⁷.2 + 2⁵⁷.2.2 + 2⁵⁷.2.2.2)

A = 2.(1 + 2 + 4 + 8) + ... + 2⁵⁷.(1 + 2 + 4 + 8)

A = 2.15 + ... + 2⁵⁷.15

A = 15.(2 + 2⁵ + ... + 2⁵⁷) chia hết cho 15

=> A chia hết cho 15

A =  2 + 2² + 2³ + ... + 2⁵⁸ + 2⁵⁹ + 2⁶⁰

A = (2 + 2² + 2³) + ... + (2⁵⁸ + 2⁵⁹ + 2⁶⁰)

A = (2.1 + 2.2 + 2.2.2) + ... + (2⁵⁸.1 + 2⁵⁸.2 + 2⁵⁸.2.2)

A = 2.(1 + 2 + 4) + ... + 2⁵⁸.(1 + 2 + 4)

A = 2.7 + ... + 2⁵⁸.7

A = 7.(2 + 2⁴ + ... + 2⁵⁸) chia hết cho 7

=> A chia hết cho 7

A = ( 2 + 2² ) + ( 2³ + 2⁴ ) + ... + ( 2⁵⁹ + 2⁶⁰ )

A = 2 . ( 1+2 ) + 2³ . (1+2) + ... + 2⁵⁹ . (1+2)

A = 2.3 + 2³.3 + ... + 2⁵⁹.3

A = (2+2³+...+2⁵⁹) . 3

vì 3 chia hết cho 3 suy ra A chia hết cho 3

Đề đâu hả bạn ?

xin lỗi bạn :((( mình ấn lộn :(((

(2x + 2) . (y - 3) = 11

Ta có : 11 = 11.1= 1.11=(-1).(-11)=(-11).(-1)

/eə/:Mary,chair,air,where,their,parents,there.

/ɪə/:beer,peers,hear,clear,bear.

1.My father studyed Math at university.

2.We were very tired so we stopped walking.

3.I tried to pick the bag up,but it was very heavy.

4.The firemen rescued the woman from the burning house.

5.The cat jumped up into the tree.

6.After the film,we walked home.

7.It was very cold so we closed the window.

8.You are late! The lesson started ten minutes ago.

9.The teacher asked a lot of questions yesterday.

10.The programme was very funny,we laughed a lot.

1 What do you prefer doing in your free time?

a. Going out c. Watching TV

b.Reading books d. Other activities

2 How many hours a day do you watch television?

a.One hours c. Three hours

b. Two hours d. More than three hours

3 Why do you watch TV?

a. I have nothing else to do. c.I like it because it's entertaining and educational

b. My parents want me to do it. d. I can go to sleep easily when I watch TV.

4 Which of the following do you like to get information from?

a. Books c.The Internet

b. Newspapers d. Television

5 How long do you think you can live without TV?

a. I cannot live without TV. c. Less than a month.

b. Less than a week. d. I don't know.

1 What do you prefer doing in your free time?

a. Going out c. Watching TV

b.Reading books d. Other activities

2 How many hours a day do you watch television?

a.One hours c. Three hours

b. Two hours d. More than three hours

3 Why do you watch TV?

a. I have nothing else to do. c.I like it because it's entertaining and educational

b. My parents want me to do it. d. I can go to sleep easily when I watch TV.

4 Which of the following do you like to get information from?

a. Books c.The Internet

b. Newspapers d. Television

5 How long do you think you can live without TV?

a. I cannot live without TV. c. Less than a month.

b. Less than a week. d. I don't know.

em moi hoc lop bay

ma bai kho

bo tay .com .vn