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\(A=\frac{1}{3}.\left(\frac{3}{2.4.6}+\frac{3}{4.6.8}+...+\frac{3}{22.24.26}\right)\)
\(A=\frac{1}{3}.\left(\frac{1}{2.4}-\frac{1}{4.6}+\frac{1}{4.6}-\frac{1}{6.8}+...+\frac{1}{22.24}-\frac{1}{24.26}\right)\)
\(A=\frac{1}{3}.\left(\frac{1}{2.4}-\frac{1}{24.26}\right)\)
\(A=\frac{1}{3}.\frac{77}{624}\)
\(A=\frac{77}{1872}\)
Trả lời :
= 7
Còn cách làm tham khảo Kiều Anh nha
#Mập
1 I went to the beach
2 No, he can't
3 There are 3 buildings at my school
1: I were on the beach.
2: No, he can ' t.
3: There are three buildings.
`= 1 - 1/2 + 1 - 1/6 + ... + 1 - 1/56`
`= 1 - 1/(1.2) + 1 - 1/(2.3) + ... + 1 - 1/(7.8)`
`= 7 - (1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4+ 1/4 - 1/5 + 1/5 - 1/6 + 1/6 - 1/7 + 1/7 - 1/8`.
`= 8 - 1/8`
`= 63/64`.
`A=1/2+5/6+11/12+19/20+29/30+41/42+55/56`
`A=1-1/2+1-1/6+1-1/12+1-1/20+1-1/30+1-1/42+1-1/56`
`A=(1+1+1+1+1+1+1)-(1/2+1/6+1/12+....+1/56)`
`A=7-(1/[1xx2]+1/[2xx3]+1/[3xx4]+....+1/[7xx8])`
`A=7-(1-1/2+1/2-1/3+1/3-1/4+....+1/7-1/8)`
`A=7-(1-1/8)`
`A=7-(8/8-1/8)`
`A=7-7/8`
`A=56/8-7/8=49/8`
I. PHONICS
1.A.this
2.A. small
3 B.door
4. C.who
5 D. flower
6.D.handsome
7. D.watch
8.A.brother
9. D. fall
10.A.nose B.flower C.hold D. cold
I. PHONICS
1.A.this B.thin C.thick D.thanks
2.A. small B. tall C.bad D.ball
3.A. room B.door C.school D.book
4.A.when B.why C.who D.where
5.A.nose B.cold C. hold D. flower
6.A. large B. bad C.fat D.handsome
7.A. Bay B. play C.stay D.watch
8.A.brother B.open C.so D.cold
9. A. take B. late C. table D. fall
10.A.nose B.flower C.hold D. cold
* Nếu sai thì thông cảm ạ :) *
1. Her name is Rosy. 2. She’s eight years old. 3. Her father is ateacher 4. Rosy’s father favorite food is fish. 5. Her mother is a nurse.
6. Rosy’s mother favorite food are vegetables and beef. 7. Her brother is six years old. 8. Rosy’s brother favorite drink is orange juice.
9. He s hamburger.
Bài nghe:
1. How can I get to the bookshop?
(Làm thế nào để tôi có thể đến hiệu sách?)
2. How can I get to the campsite?
(Làm thế nào để tôi có thể đến khu cắm trại?)
Lời giải chi tiết:
1. c 2. a
Odd one out
1. A.scarf B.sandals C.boots D.shoes
2. A.soccer B.tennis C.badminton D.sport
3. A.elephant B.animal C.dolphin D.shark
4. A.play B.seafood C.sandcastle D.beach ball
5.A.violin B.guitar C.music D.piano
6. A.football B.table tennis C.volleyball D.play
7. A.music B.english C.books D.physics
8. A. party B. invite C. complete D. money câu này chịu
9. A.flowers B. visit C. clothes D.sport câu này chịu
10. A. their B. me C. his D. our
11. A. coat B. sandals C. boots D. shoes
11.A.cycle B.ski C.skate D.chess
12.A. giraffe B. seafood C. dolphin D. shark
13.A.play B. badminton C.football D. chess
14. A.english B.music C.subject D.history
nếu sai cho mình xin lỗi
1. A.scarf B.sandals C.boots D.shoes
2. A.soccer B.tennis C.badminton D.sport
3. A.elephant B.animal C.dolphin D.shark
4. A.play B.seafood C.sandcastle D.beach ball
5.A.violin B.guitar C.music D.piano
6. A.football B.table tennis C.volleyball D.play
7. A.music B.english C.books D.physics
8. A. party B. invite C. complete D. money
9. A.flowers B. visit C. clothes D.sport
10. A. their B. me C. his D. our
11. A. coat B. sandals C. boots D. shoes
11.A.cycle B.ski C.skate D.chess
12.A. giraffe B. seafood C. dolphin D. shark
13.A.play B. badminton C.football D. chess
14. A.english B.music C.subject D.history
1. Where do your mother often buy this book? => Where does your mother often buy this book?
2. Are Tom studying? => Is Tom studying?
3. Hoa not have good speaking skill. => Hoa does not have good speaking skill
4. The young girl not writing the letter now. => The young girl is not writing the letter now.
5. Are Lam fond of listening music?=> Is Lam fond of listening to music?
6. They studies math=> They study math
7. What you usually do in the morning? => What do you usually do in the morning?
8. They are traveling to London. => Th ey are travelling to London.
9. The plane is land now.=> The plane is landing now
10. Why she is saying loudly?=> Why is she saying loudly?
1. Where do your mother often buy this book?
=> Where does your mother often buy this book?
2. Are Tom studying English now?
=>Is tom studying English now?
3. Hoa not have good speaking skill.
=>Hoa doesn't have good speaking skill.
4. The young girl not writing the letter now.
=> That young girl isn't writing the letter now.
5. Are Lam fond of listening music?
=> Does Lam fond of listening to music?
6. They studies math once time a week.
=> They study math once time a week.
7. What you usually do in the morning?
=> What do you usually do in the morning?
8. They are traveling to London.
=>They are travelling to London.
9. The plane is land now.
=> The plane is landing now.
10. Why she is saying loudly?
=> why is she saying loudly?
Hok tốt
Nhớ rằng: \(\frac{n}{a.\left(a+n\right)}=\frac{1}{a}+\frac{1}{a+n}\)
Ta có: \(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{90}\)
\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\)
Áp dụng công thức trên, ta có:
\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\)
\(A=1-\frac{1}{10}=\frac{9}{10}\)
\(Â=\frac{9}{10}\)