\(A=\left(5^2+5^3\right)+\left(5^4+5^5\right)+...+\left(5^{2020}+5^{2021}\right)\\ =5^2.\left(1+5\right)+5^4.\left(1+5\right)+...+5^{2020}.\left(1+5\right)\\ =5^2.6+5^4.6+...+5^{2020}.6\\ =6.\left(5^2+5^4+...+5^{2020}\right)⋮6\)

Đổi 1,25 = 125/100=5/4

Số lớn là:

1,25: (5-4). 5=6,25

Số bé là:

1,25: (5-4) . 4= 5

Đ/s...

Tick giúp em nhé

1 It is responsible for 20 percent of fresh water flowing into the world's oceans

2 No, it doesn't

3 It is about 6400 km long

4 It has more than 200 tributaries

sao ko tự làm ik đẽ thế mà phải hỏi

bài dễ thế mà cx phải hỏi, tự nghĩ đi

Ex4

1 has

2 am not solving

3 comes

4 begins

5 do you wake up

6 are you doing

7 don't work - am working

8 is not sleeping

9 do you review

10 is working

11 takes

12 is

Ex5

1 more exciting

2 more fantastic

3 better

4 faster

5 more valuable

6 larger

7 easier

8 farther

9 bigger

10 taller

11 longer

12 more dangerous

13 luckier

14 bigger - cheaper

15 more famous

Ex1

1 A

2 D

3 A

4 A

5 A

Ex2

1 A

2 A

3 A

3 C

4 A

Ex3

1 A

2 B

3 C

4 B

5 A

6 D

7 B

8 B

9 A

10 C

11 D

12 C

13 A

14 C

15 D

16 C

17 A

18 B

19 A

20 D

21 C

22 B

Prepare a map or we will be lost soon

A = - 5²² - { - 222 - [ - 122 - (100 - 5²²) + 2022] }

A = - 5²² - { -222 - [- 122 - 100 + 5²² ] + 2022}

A = - 5²² - { -222 - { - 222 + 5²² } + 2022}

A = - 5²² - {- 222 + 222 - 5²² + 2022}

A = -5²² + 5²² - 2022

A = - 2022

B = 1 + \(\dfrac{1}{2}\)(1 + 2) + \(\dfrac{1}{3}\).(1 + 2 + 3) + ... + \(\dfrac{1}{20}\).(1 + 2+ 3 + ... + 20)

B = 1+\(\dfrac{1}{2}\)\(\times\)(1+2)\(\times\)[(2-1):1+1]:2+ ... + \(\dfrac{1}{20}\)\(\times\) (20 + 1)\(\times\)[(20-1):1+1]:2

B = 1 + \(\dfrac{1}{2}\) \(\times\) 3 \(\times\) 2:2 + \(\dfrac{1}{3}\) \(\times\)4 \(\times\) 3 : 2+....+ \(\dfrac{1}{20}\) \(\times\)21 \(\times\) 20 : 2

B = 1 + \(\dfrac{3}{2}\) + \(\dfrac{4}{2}\) + ....+ \(\dfrac{21}{2}\)

B = \(\dfrac{2+3+4+...+21}{2}\)

B = \(\dfrac{\left(21+2\right)\left[\left(21-2\right):1+1\right]:2}{2}\)

B = \(\dfrac{23\times20:2}{2}\)

B = \(\dfrac{23\times10}{2}\)

B = 23