trong các số sau, nhứng số nào chia hết cho cả 2:3 và 5
510; 172; 1705; 1020; 1310
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Khách
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BT
4
NN
Nguyễn Ngọc Anh Minh
CTVHS
VIP
2 tháng 12 2021
A=1+2(1+2)+2^3(1+2)+2^5(1+2)+...+2^99(1+2)=
=1+3(2+2^3+2^5+...+2^99)
=> A chia 3 dư 1
BN
1
LT
2
1 tháng 12 2021
Gọi số hàng dọc nhiều nhất có thể xếp được là a (hàng)
*Ta phải có 114 ⋮ a , 135 ⋮ a , 117 ⋮ a và a lớn nhất
*=> a = ƯCLN(114,135,117) = 9
* a = 9
*Xếp được nhiều nhất thành 9 hàng dọc
*Lúc đó khối 6 có 144 ; 9 = 16 (hàng)
Khối 7 có 135 : 9= 25 (hàng)
Khối 8 có 117 :9 = 13 (hàng )
CT
1
2 tháng 12 2021
a) -5.(-x + 20) = -21 +16
-5.(-x + 20) = -5
-x + 20 = -5 : -5
-x + 20 = 1
-x = -19
suy ra x = 19
NH
1 tháng 12 2021
Gọi số học sinh là x (x thuộc N*; 700 < x < 800)
Ta có:
x chia hết cho 40
x chia hết cho 45
=> x thuộc BC (40;45)
Có : 40 = 23 x 5
45 = 32 x 5
=> BCNN (40;45) = 23 x 32 x 5 = 360
=> BC (40;45) = {0;360;720;1080;...}
Mà 700 < x < 800
=> x = 720
Vậy số học sinh là 720 học sinh.
TD
1 tháng 12 2021
+ Gọi số học sinh của trường đó là a ( học sinh , a ∈ N* , 700 ≤ a ≤ 800 )
+ Nếu xếp 40 học sinh hay 45 học sinh lên 1 chiếc xe đều vừa đủ => a ⋮ 40 ; a ⋮ 45
=> a ∈ BC(40 ; 45)
+ Ta có:
40 = 23 . 5
45 = 32 . 5
=> BCNN(40 ; 45) = 23 . 32 . 5 = 360
=> a ∈ BCNN(40 ; 45) = B(360) = { 0 ; 360 ; 720 ; 1080 ; 1440 ; ..... }
Mà 700 ≤ a ≤ 800
nên a = 720
+ Vậy số học sinh của trường đó là 720 học sinh.
HN
1
Ex1: Complete the sentences with: a, an, some, any
1. We didn’t buy …………flowers.
2. This evening I’m going out with ………….friends of mine.
3. “Have you seen ………..good films recently?”
– “No, I haven’t been to the cinema for ages”.
4. I didn’t have ……………money, so I had to borrow………..
5. Can I have ………milk in my coffee, please?
6. I was too tired to do………work.
7. There is .................. banana in the basket.
8. I need ..................tea.
9. Are there ..................tomatoes in the fridge?
10. We have .........rice, but we don't have ......meat.
11. There's ..................orange on the table.
12. I'd ..................apple juice.
13. He has ............TV and ............computer.
14. Would you ..................ice- cream?
15. I have............... friends in Hue.
16. Do you have ...............dogs or cats at home?
17. Would you ..................cup of tea?
18. I would .................. cakes, please.
19. Can I have ............glass of milk?
20. Thank you. And .........box of chocolates would be fine.
21. I don't have ............... paper.
22. Is there ............... petrol in the car?
23. I buy ...............fruit, but I don't have ...............vegetables.
24. Do you have ............... stamps? I need two.
25. I need ...............butter to make a cake.
26. I don't have ...............free time today. Sorry.
27. Are there............... potatoes in the basket?
28. There is ...............ink-pot on the table.
EX2: Find and corect the mistakes
Câu 1: How much is a bowl of fried rice? - They is 2,500 dong.
A B C D
Câu 2: What is you favorite food?
A B C D
Câu 3: What weather are you ?
A B C D
Câu 4: Are there some books on the table.
A B C D
Câu 5: He is going to visits Ngoc Son temple.
A B C D
Câu 6: Are there some books on the table.
A B C D
EX3: Complete the sentences with: “much, many, few, a few, little, a little”
1. He isn’t very popular. He has ………..friends.
2. Ann is very busy these days. She has ………..free time.
3. Did you take …………….photographs when you were on holiday?
4. The museum was very crowded. There were too………..people.
5. Most of the town is modern. There are …………..old buildings.
6. We must be quick. We have………..time.
7. Listen carefully, I’m going to give you ……….advice.
8. Do you mind if I ask you……….questions?
9. This town is not a very interesting place to visit, so …….tourists come here.
10. I don’t think Jill would be a good teacher. She’s got …………..patience.
11. “Would you milk in your coffee?” – “yes, please. ………….”
12. This is a very boring place to live. There’s ………….to do.
Trả lời :
Các số đó là : 510; 1020
# Hok tốt !