2^30-2^29+2^28-2^27+...-2^3+2^2
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15 tháng 12 2021 lúc 18:44
A = 1 - 2 + 22 - 23 + 24 - 25 +...+ 228 - 229 + 230
\(2A=2-2^2+2^3-...-2^{30}+2^{31}\\ \Leftrightarrow2A+A=2-2^2+2^3-...-2^{30}+2^{31}+1-2+2^2-...-2^{29}+2^{30}\\ \Leftrightarrow3A=2^{31}+1\\ \Leftrightarrow A=\dfrac{2^{31}+1}{2}\)
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bài 1: tìm X
a) /x+2/+|x–5/=x-1
b) /x+2/+/x +5| =2x
c) /2x+4/ + /x –3/=0
d)x+1+/x+2/+...+/x+98/+/x+99/=99x
g)(x+1)+(x+2)+....+(x+98)+(x+99)=0
h)(x-3)+(x-2)+(x-1)+... +10+11=11
nhờ các bạn giúp mình nhé, mình đang cần gấp
Đốt cháy hoàn toàn 5,4g Al trong bình cs chứa khí Oxi ,sau khi phản ứng kthúc thu đc Al xit
a: Lập PTHH
b: Tính thể tích khí Oxi cần dùng ở đktc
c: Tính khối lượng Al oxit tạo thành ?
a nhé mình ko chắc lắm
đâu phải chọn abc j đâu. mấy cái này là câu hỏi hết mà=/
uk nhỉ tui ko để ý
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Đổi thành Câu hỏi đuôi 17, Bill couldn’t have prevented it 18, Bill hasn’t got a car 19, there weren’t any mosquitoes 20, George hadn’t been there before 21, you would’t mind helping me with this 22, you take sugar in tea 23, but you don’t take it in coffee 24, it never works very well 25, mary hardly ever cooks 26, she’d save money if she bought fresh food 27, neither of them offered to help you 28, he hardly ever leaves the house29, nothing went wrong 30, there used to be trees here
Đọc tiếp
Đổi thành Câu hỏi đuôi
17, Bill couldn’t have prevented it
18, Bill hasn’t got a car
19, there weren’t any mosquitoes
20, George hadn’t been there before
21, you would’t mind helping me with this
22, you take sugar in tea
23, but you don’t take it in coffee
24, it never works very well
25, mary hardly ever cooks
26, she’d save money if she bought fresh food
27, neither of them offered to help you
28, he hardly ever leaves the house
29, nothing went wrong
30, there used to be trees here
Đổi thành Câu hỏi đuôi
17, Bill couldn’t have prevented it
=> Bill couldn’t have prevented it, could he?
18, Bill hasn’t got a car
=> Bill hasn’t got a car, has he?
19, there weren’t any mosquitoes
=> There weren’t any mosquitoes, were there?
20, George hadn’t been there before
=> George hadn’t been there before, had he?
21, you would’t mind helping me with this
=> You would’t mind helping me with this, would you?
22, you take sugar in tea
=> you take sugar in tea, don't you?
23, but you don’t take it in coffee
=> But you don’t take it in coffee, do you?
24, it never works very well
=> It never works very well, does it?
Chào em, em tham khảo nhé!
17. Bill couldn't have prevented it, could he?
18. Bill hasn't got a car, has he?
19. There weren't any mosquitoes, were there?
20. George hadn't been there before, had he?
21. You wouldn't mind helping me with this, would you?
22. You take sugar in tea, don't you?
23. But you don't take it in coffee, do you?
24. It never works very well, does it?
25. Mary hardly ever cooks, does she?
26. She'd save money if she bought fresh food, didn't she?
27. Neither of them offered to help you, did they?
28. He hardly ever leaves the house, does he?
29. Nothing went wrong, did they?
30. There used to be trees here, didn't there?
Chúc em học tốt và có những trải nghiệm tuyệt vời tại olm.vn!
25, mary hardly ever cooks
=> Mary hardly ever cooks, doesn't she?
26, she 'd save money if she bought fresh food
=> She’d save money if she bought fresh food, hadn't she?
27, neither of them offered to help you
=> Neither of them offered to help you, did they?
28, he hardly ever leaves the house
=> He hardly ever leaves the house, doesn't he?
29, nothing went wrong
=> Nothing went wrong, didn't it?
30, there used to be trees here
=> There used to be trees here, didn't it?
có bao nhieu hình tứ giác:
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có bao nhieu hình tứ giác:
tìm SHT x, sao cho tổng của của số đó vs số nghịch đảo của nó là một số nguyên
VD: 23, 24, 26 đến 29, 33, 58 đến 76
BT: 135, 139 đến 143, 148 đến 150, 156 đến 160, 212 đến 228, 230 đến 271, 273 đến 275, 277, 278
VD và BT là ý j vậy
e ns rõ đề tý để chj còn làm
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Chứng minh 1/101+1/102+1/103+...+1/229+1/230
Bài 1: Điền dạng đúng của từ trong ngoặc. 1. She (not study) ………. on Saturday. 2. He (have) ………. a new haircut today. 3. I usually (have) ……….breakfast at 6.30. 4. Peter (not/ study)……….very hard. He never gets high scores. 5. My mother often (teach)……….me English on Saturday evenings. 6. I like Math and she (like)……….Literature. 7. My sister (wash)……….the dishes every day. 8. They (not/ have)……….breakfast every morning. Bài 2: Viết lại câu, điền đúng dạng từ trong ngoặc. 1. My brothers (sleep)...
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Bài 1: Điền dạng đúng của từ trong ngoặc. 1. She (not study) ………. on Saturday. 2. He (have) ………. a new haircut today. 3. I usually (have) ……….breakfast at 6.30. 4. Peter (not/ study)……….very hard. He never gets high scores. 5. My mother often (teach)……….me English on Saturday evenings. 6. I like Math and she (like)……….Literature. 7. My sister (wash)……….the dishes every day. 8. They (not/ have)……….breakfast every morning. Bài 2: Viết lại câu, điền đúng dạng từ trong ngoặc. 1. My brothers (sleep) on the floor. (often) =>____________ 2. He (stay) up late? (sometimes) => __________ 3. I (do) the housework with my brother. (always) => __________ 4. Peter and Mary (come) to class on time. (never) => __________ 5. Why Johnson (get) good marks? (always) => __________ 6. You (go) shopping? (usually) => __________ 7. She (cry). (seldom) => __________ 8. My father (have) popcorn. (never) => __________ Bài 3. Hoàn thành các câu sau sử dụng động từ trong ngoặc chia ở thì hiện tại tiếp diễn 1.My grandfather ________________ (buy) some fruits at the supermarket. 2.Hannah ________________ (not study) French in the library. She’s at home with her classmates. 3.__________________ (she, run) in the park now? 4.My dog ________________ (eat) now. 5.All of Jack’s friends ________________ (have) fun at the concert right now. 6.My children ________________ (travel) around Asia now. 7.My little brother ________________ (drink) milk at the moment. 8.Listen! Our teacher ________________ (speak). Bài 4: Chia động từ trong ngoặc ở thì hiện tại tiếp diễn hoặc thì hiện tại đơn 1.It often ________________ in Ireland (rain). ________________ there now (rain)? 2.Susan ________________ to her parents every Sunday night (write). 3.He ________________ tennis with Sue. (play) now. 4.She usually__________________ in Northbridge but she ________________ with friends at the moment. (live, stay) 5.Hurry up! The teacher ________________ to begin (wait). 6.I ________________ a word Tim says (not believe). 7.The new lawnmower ________________ well at the moment. (work) 8.What ________________ do for a living? (you, do) 9.Look! She ________________ in the non- smoking area (smoke) 10.My brother ________________ to Italy twice a week. (go) 11.He usually ________________ out on Saturday night. (go) 12.She ________________ by train to Liverpool this weekend. (depart)
1. 1) doesn't study
2) has
3) have
4) doesn't study
5) teaches
6) s
7)washes
8) don't have
1. doesn't study
2. has
3. have
4. doesn't study
5. teaches
6.
7. washed
8. don't have
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Tìm các số tự nhiên a,b,c sao cho 228 ≤ a < b < c ≤ 230
A. a=228;b=229;c=230
B. a=227;b=228;c=229
C. a=229;b=230;c=231
D. Không tồn tại a;b;c thỏa mãn đề bài
Đáp án cần chọn là: A
Từ đề bài, ta thấy các số tự nhiên lớn hơn hoặc bằng 228 và nhỏ hơn hoặc bằng 230 là
228;229;230.
Mà a<b<cnên ta có a=228;b=229;c=230.
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1. do / you / how / learn / vocabulary ________________________________?
2. how / speaking / you / practise / do ________________________________?
3. do / you / reading / practise / how ________________________________?
4. English / learn / do / why / you ________________________________?
làm giúp milk nha! :)))
1. do / you / how / learn / vocabulary _____How do you learn vocabulary___?
2. how / speaking / you / practise / do _____How do you practise speaking____?
3. do / you / reading / practise / how ____How do you practise reading______?
4. English / learn / do / why / you _____Why do you learn English____?
1.How do you learn vocabulary 2. How do you practise speaking 3.How do you practise reading 4.why do you learn English
1 , How do you learn vocabulary ?
2 , How do you practise speaking ?
3 , How do you practise reading ?
4 , Why do you learn English ?