=781/3125

5A=(1/5+1/25+1/125+1/625+1/3125)*5

5A=(1+1/5+1/25+1/125+1/625)

5A-A=(1+1/5+1/25+1/125+1/625)-(1/5+1/25+1/125+1/625+1/3125)=1-1/3125

4A=1-1/3125=3124/3125

A=3124/3125:4=781/3125.

A = 3/1×5 + 3/5×9 + 1/9×13 + ... + 9/97×101 + 3/101×105

A = 3/4 × (4/1×5 + 4/5×9 + 4/9×13 + ... + 4/97×101 + 4/101×105)

A = 3/4 × (1 - 1/5 + 1/5 - 1/9 + 1/9 - 1/13 + ... + 1/97 - 1/101 + 1/101 - 1/105)

A = 3/4 × (1 - 1/105)

A = 3/4 × 104/105

A = 26/35

B = 1/5 + 1/25 + 1/125 + 1/625 + 1/3125 + 1/15625

5B = 1 + 1/5 + 1/25 + 1/125 + 1/625 + 1/3125

5B - B = (1 + 1/5 + 1/25 + 1/125 + 1/625 + 1/3125) - (1/5 + 1/25 + 1/125 + 1/625 + 1/3125 + 1/15625)

4B = 1 - 1/15625

4B = 15624/15625

B = 15624/15625 : 4

B = 3906/15625

C = 1 + 2 + 4 + 8 + 16 + ... + 2048 + 4096

2C = 2 + 4 + 8 + 16 + 32 + ... + 4096 + 8192

2C - C = (2 + 4 + 8 + 16 + 32 + ... + 4096 + 8192) - (1 + 2 + 4 + 8 + ... + 2048 + 4096)

B = 8192 - 1

B = 8191

Soyeon_Tiểu Bàng Giải lm đúng òi

mik ko hỉu sao bn tên mắm tôm nữa?

bn lên trang wed h.vn để tham khảo nhé!

chưa đâu bn còn phải đăng nhập nữa ấy

hok tốt!

*Mylinh*

Cách 1:

Trại có số con gà là : 3125 x 2/5 = 1250 (con gà)

Trại có số vịt là : 3125 -  1250 = 1875(con vịt)

Cách 2:

Số vịt chiếm : 1-2/5 = 3/5 (tổng số)

Trại có số vịt là : 3125 x 3/5 = 1875 (con vịt)

mk cần gấp các bạn nhanh lên

2) \(\frac{3}{1\times3}+\frac{3}{3\times5}+\frac{3}{5\times7}+...+\frac{3}{99\times101}+\frac{3}{101\times103}\)

\(=\frac{3}{2}\times\left(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+...+\frac{2}{101\times103}\right)\)

\(=\frac{3}{2}\times\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{101}-\frac{1}{103}\right)\)

\(=\frac{3}{2}\times\left(1-\frac{1}{103}\right)\)

\(=\frac{3}{2}\times\frac{101}{103}\)

\(=\frac{303}{206}\)

1. They __________ the bus yesterday.

A. don’t catch B. weren’t catch C. didn’t catch D. not catch

2. My sister __________ home late last night.

A. comes B. come C. came D. was come

3. My father __________ tired when I __________ home.

A. was – got B. is – get C. was – getted D. were – got

4. What __________ you __________ two days ago?

A. do – do B. did – did C. do – did D. did – do

5. Where __________ your family __________ on the summer holiday last year?

A. do – go B. does – go C. did – go D. did – went

6. "When ________________?" - "In 1928."

A. did penicillin discovered B. did penicillin discover

C. was penicillin discovered D. penicillin was discovered

7. I had met my old friend before I ------ to see you yesterday.

A. have gone B. went C. had gone D. go

8. This is the house that Jack ______ three years ago.

A. built B. had built C. builds D. was building

9. The Second World War _____ in 1939.

A. start B. starts C. has started D. started

10. Her daughter ____________ in 2014.

A. is born B. has born C. was born D. born

11. When we _____ up this morning, the sun was shining.

A. had got B. got C. were getting D. has got

12. They _____________ a new house two years ago.

A. buy B. are buying C. have bought D. bought

13. They _________ here a month ago.

A. are coming B. have came C. came D. come

14. When I was young, I ______to be a singer .

A. had wanted B. was wanting C. have wanted D. wanted

15. How fast was she driving when the accident________?

A. happened B. was happening C. happens D. had happened

THANKS

\(5^x.5^{x+1}.5^{x+2}=3125\)

\(\Rightarrow5^{x+x+1+x+2}=5^5\)

\(\Rightarrow5^{3x+3}=5^5\)

\(\Rightarrow3x+3=5\)

\(\Rightarrow3x=2\)

\(\Rightarrow x=\frac{2}{3}\)

=> 5^x.5^x+1.5^x+2 = 5⁵

<=> 5^x+x+1+x+2 = 5⁵

=> x+x+1+x+2 = 5

=> 3x+3=5

3x = 5-3

3x = 2

x = 2:3

x = 2/3

mik lớp 5 nhg ko bt gì :))

có cái nịt hoặc chẳng có cái gì.