=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.

lớp 4 mÀ

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

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

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)

Cách 1 : 
Coi số gà và vịt là \(\frac{5}{5}\) số vịt chiếm số phần là :

\(\frac{5}{5}-\frac{2}{5}=\frac{3}{5}\)

Số vịt được nuôi trong trang trại đó là :

\(3125\times\frac{3}{5}=1875\) ( con vịt )

Đáp số : 1875 con vịt

Cách 2 :

Số gà được nuôi trong trang trại đó là :

\(3125\times\frac{2}{5}=1250\) ( con gà )

Số vịt được nuôi trong trang trại đó là :

3125 - 1250 = 1875 ( con vịt )

Đáp số : 1875 con vịt 

Học tốt nhé bạn !

mk cần gấp các bạn nhanh lên

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

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

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

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

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

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

bạn viết ko rõ lắm

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

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

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

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

\(\Rightarrow3x+3=5\)

\(\Rightarrow3x=2\)

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

=> 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

5^x . 5^x+1.5^x+2=3125

5^x . 5^x .5¹ + 5^x .5²=3125

5^x  . ( 5¹ + 5² ) = 3125

5^x . 30 = 3125

5^x = 3125 : 30

Bạn ơi đề này chắc ra du rùi

mik lớp 5 nhg ko bt gì :))

có cái nịt hoặc chẳng có cái gì.

2 cái quả cho 2 bạn rồi thì còn cái đĩa cho nốt người thứ 3 chứ cong gì nưa

cái này cần IQ nha thông minh nới được

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