Đặt `A= 1/3 + 1/(3^2) + 1/(3^3) + ... + 1/(3^99) + 1/(3^100)`

`3A=  3. (1/3 + 1/(3^2) + 1/(3^3) + ... + 1/(3^99) + 1/(3^100))`

`3A=  1 + 1/3 + 1/(3^2) + ... + 1/(3^98) + 1/(3^99)`

`3A - A = (1 + 1/3 + 1/(3^2)+... + 1/(3^98) + 1/(3^99)) - (1/3 + 1/(3^2) + 1/(3^3) + ... + 1/(3^99) + 1/(3^100))`

`2A = 1 - 1/(3^100)`

`A = (1 - 1/(3^100))/2`

Vậy: `1/3 + 1/(3^2) + 1/(3^3) + ... + 1/(3^99) + 1/(3^100) = (1-1/(3^100))/2`

   A =         \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + \(\dfrac{1}{3^3}\) + ... + \(\dfrac{1}{3^{99}}\) + \(\dfrac{1}{3^{100}}\)

3A =   1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\)+...+ \(\dfrac{1}{3^{98}}\) + \(\dfrac{1}{3^{99}}\)

3A - A = (1+ \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + ...+\(\dfrac{1}{3^{98}}\) + \(\dfrac{1}{3^{99}}\)) - (\(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\)+..+\(\dfrac{1}{3^{99}}\)+\(\dfrac{1}{3^{100}}\))

A.(3 - 1) = 1 + \(\dfrac{1}{3}\)+\(\dfrac{1}{3^2}\)+..+\(\dfrac{1}{3^{98}}\)+ \(\dfrac{1}{3^{99}}\) - \(\dfrac{1}{3}\) - \(\dfrac{1}{3^2}\) - ...- \(\dfrac{1}{3^{99}}\) - \(\dfrac{1}{3^{100}}\)

A x 2 =  (1 - \(\dfrac{1}{3^{100}}\)) + (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) + (\(\dfrac{1}{3^{98}}\) - \(\dfrac{1}{3^{98}}\)) + (\(\dfrac{1}{3^{99}}\) - \(\dfrac{1}{3^{99}}\))

A x 2 = 1 - \(\dfrac{1}{3^{100}}\) + 0 + 0 + ..+ 0

A x 2 = 1 - \(\dfrac{1}{3^{100}}\)

A = \(\dfrac{1}{2}\) - \(\dfrac{1}{2.3^{100}}\) 

C

\(10\) chia hết cho 5 nên \(10^{2021}\) chia hết cho 5

Mà 8 ko chia hết cho 5

Nên \(10^{2021}+8\) không chia hết cho 5

D đúng

   ƯC (42, 55, 91)=1

A={1;3;2}

1 danh từ (noun)

2động từ( verb)

3 tính từ(adjective)

4 trạng từ( adverb)

5 Giới từ( preposition)

6 Từ hạn định( determiner)

7 đại từ( pronoun)

8 Liên từ( con junction)

9(Thán từ(interjection)

...

Bài dạng của từ đúng ko em

a) He is from Britain, but most people thought he is from America

b) If you are Japanese, you will be thought a polite person

c) Because we are Russian, we are thought to love drinking Vodka 

ai trả lời được tick nha 

là học chăm vào đừng chs game nữa

Complete the second sentence so that it means the same as the first one. Use the word in brackets. (1 point)

Question 1: The school has a science lab for experiments. (There)  

➝ _____There is a science lab_________ for experiments in the school.

Question 2: Are there new computers in the library? (have)

➝ _______Does the library have new computers________?

Question 3: The camera is on the desk. The camera belongs to An. (An’s)

➝ _______An's camera is on________ the desk. 

Question 4: Tony doesn’t eat pizza for breakfast. Tony doesn’t eat chocolate for breakfast. (or)

➝ Tony  ________doesn't either pizza or chocolate_______ for breakfast.

Question 1: The school has a science lab for experiments. (There)  

➝ ___There is a science lab____________ for experiments in the school.

Question 2: Are there new computers in the library? (have)

➝ ____Does the library has new computers___________?

Question 3: The camera is on the desk. The camera belongs to An. (An’s)

➝ _______An's camera is on________ the desk. 

Question 4: Tony doesn’t eat pizza for breakfast. Tony doesn’t eat chocolate for breakfast. (or)

➝ Tony  ___doesn't eat pizza or chocolate____________ for breakfast.

Tham khảo ạ:

My favourite character from my book is Margot Robbie. She is a nice character and many people also love her. She loves her profession very much. I love her because she really beautiful.