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

meme sea

hello

Hiệu của số lớn nhất và số bé nhất là:

` 2 + 2 = 4`

Số thứ nhất là:

`(600 - 4):2 = 298`

Số thứ hai là:

`298 + 2 = 300`

Số thứ ba là:

`300 + 2 = 302`

Đáp số: Số thứ nhất: `298;` số thứ hai: `300;` số thứ ba: `302`

19 has worked

20 have lived - was

21 isn't - is cooking

22 Do you know - is talking

23 broke - was playing

24 has just repaired

25 washes

26 was listening 

27 are playing

28 Have you cried

29 is living - prefers

30 wouldn't have finished

31 was watching

32 is going to invite

33 know - to answer

34 are going 

35 have collected

36 is repairing - has been working

37 was walking - saw

38 haven't finished

39 haven't seen - left

40 have been walking

41 have been learning

42 have stayed

43 left

44 has driven

45 is coming

46 was working

47 was fishing

48 will like

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

25 = 5²

Ư(25) = {1; 5; 25}

Vì 3311 = 11 . 301 nên 3311 có ước là 11 và 301. Vậy 3311 là một hợp số.

Ta có: `3311 = 11 .301`

`->` Số `3311` là hợp số.

hợp số bạn nhé