
Vũ Hà Vy Anh 13 hour before (22:28)

Kaito Kid 14 hour before (22:08)
Dear friend ! Is the triangle or rectangle ?

MCP Yesterday at 20:22
We have : a ≤ ≤ c + 2 b + 1 ≤ ≤ c + 2 c + 2 = c + 2 => a + b + 1 + c + 2 ≤ ≤ c + 2 + c + 2 + c + 2 => (a + b + c) + (1 + 2) ≤ ≤ 3c + 6 => 1 + 3 ≤ ≤ 3c + 6 => 4 ≤ ≤ 3c + 6 => − 2 3 −23 ≤ ≤ c => Minc = − 2 3 −23 => a + b +( − 2 3 −23) = 1 => a + b = 5 3 53 With a = b + 1 => a + b = 5 3 53 => b + 1 + b = 5 3 53 => b = 1 3 13 => a = 4 3 43 (1) With a < b + 1 => b + 1 + b < 5 3 53 => b < 1 3 13 => a < 4 3 43 (2) From (1) and (2) => b ≤ 1 3 ≤13 and a ≤ 4 3 a≤43 So the smallest value of c = − 2 3 −23 When b ≤ 1 3 ≤13 and a ≤ 4 3
NGUYỄN SANH KIÊN selected this answer. 
Nếu bây giờ ngỏ ý . Liệu có còn kịp không 23 hour before (12:35)We have : a ≤ ≤ c + 2 b + 1 ≤ ≤ c + 2 c + 2 = c + 2 => a + b + 1 + c + 2 ≤ ≤ c + 2 + c + 2 + c + 2 => (a + b + c) + (1 + 2) ≤ ≤ 3c + 6 => 1 + 3 ≤ ≤ 3c + 6 => 4 ≤ ≤ 3c + 6 => − 2 3 −23 ≤ ≤ c => Minc = − 2 3 −23 => a + b +( − 2 3 −23) = 1 => a + b = 5 3 53 With a = b + 1 => a + b = 5 3 53 => b + 1 + b = 5 3 53 => b = 1 3 13 => a = 4 3 43 (1) With a < b + 1 => b + 1 + b < 5 3 53 => b < 1 3 13 => a < 4 3 43 (2) From (1) and (2) => b ≤ 1 3 ≤13 and a ≤ 4 3 a≤43 So the smallest value of c = − 2 3 −23 When b ≤ 1 3 ≤13 and a ≤ 4 3

Futeruno Kanzuki Yesterday at 20:04
We have :
a \(\le\) c + 2
b + 1 \(\le\) c + 2
c + 2 = c + 2
=> a + b + 1 + c + 2 \(\le\) c + 2 + c + 2 + c + 2
=> (a + b + c) + (1 + 2) \(\le\) 3c + 6
=> 1 + 3 \(\le\) 3c + 6
=> 4 \(\le\) 3c + 6
=> \(\dfrac{2}{3}\) \(\le\) c
=> Min_{c} = \(\dfrac{2}{3}\)
=> a + b +( \(\dfrac{2}{3}\)) = 1
=> a + b = \(\dfrac{5}{3}\)
With a = b + 1
=> a + b = \(\dfrac{5}{3}\)
=> b + 1 + b = \(\dfrac{5}{3}\)
=> b = \(\dfrac{1}{3}\) => a = \(\dfrac{4}{3}\) (1)
With a < b + 1
=> b + 1 + b < \(\dfrac{5}{3}\)
=> b < \(\dfrac{1}{3}\) => a < \(\dfrac{4}{3}\) (2)
From (1) and (2)
=> b \(\le\dfrac{1}{3}\) and \(a\le\dfrac{4}{3}\)
So the smallest value of c = \(\dfrac{2}{3}\)
When b\(\le\dfrac{1}{3}\) and \(a\le\dfrac{4}{3}\)
nandemonai selected this answer. 
nandemonai Yesterday at 20:09
thanks
donald trump
Yesterday at 16:42

Đào Trọng Nghĩa Yesterday at 19:24
Mình chả biết

falcon handsome Yesterday at 17:20
this question very easy
donald trump
Yesterday at 16:39

Đào Trọng Nghĩa Yesterday at 19:28
Mình chịu lớp mấy zậy


Phan Thanh Tinh Yesterday at 22:39
b^{3} = 3375 = 15^{3} => b = 15 => a = 13 ; c = 17 => ac = 221
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Thám Tử THCS Nguyễn Hiếu Yesterday at 20:52
The odd number between the six remaining numbers is:
1337 : 7 = 191
So 7 consecutive numbers are 185 ; 187 ; 189 ; 191 ; 193 ; 195 ; 197
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Nễu Lả Ánh 23 hour before (12:41)
The odd number between the six remaining numbers is:
1337 : 7 = 191
So 7 consecutive numbers are 185 ; 187 ; 189 ; 191 ; 193 ; 195 ; 197

Phan Thanh Tinh Yesterday at 22:29
Let a (cm) be the largest possible square size
=> a = GCD (140 ; 240) = 20
So the largest size of the square's edge is 20 cm.Then the smallest number of squares can be cut from the cardboard is :
140 x 240 : 20^{2} = 84
Answer : 20 cm ; 84 squares
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Nếu bây giờ ngỏ ý . Liệu có còn kịp không 23 hour before (12:36)
Let a (cm) be the largest possible square size
=> a = GCD (140 ; 240) = 20
So the largest size of the square's edge is 20 cm.Then the smallest number of squares can be cut from the cardboard is :
140 x 240 : 202 = 84
Answer : 20 cm ; 84 squares
donald trump
Yesterday at 13:47

»ﻲ2004#ﻲ« 6 hour before (06:10)
We have : abcabc = abc x 1001 = abc x 7 x 11 x 13
Because abc is a prime number,the number of divisors of abcabc is :
(1 + 1)4 = 16

Nếu bây giờ ngỏ ý . Liệu có còn kịp không 23 hour before (12:29)
Let a,b,c be the number of the correctly answered questions , unanswered questions , incorrectly answered questions of a participant respectively
Then the participant's total score is 5a + b  c with a + b + c = 30
If a is odd,then 5a and b + c are odd,so b  c is odd and 5a + b  c is even
If a is even,then 5a and b + c are even,so b  c is even and 5a + b  c is even
From 2 cases,we know that the total score of all participants is always an even number

Phan Thanh Tinh Yesterday at 06:12
Let a,b,c be the number of the correctly answered questions , unanswered questions , incorrectly answered questions of a participant respectively
Then the participant's total score is 5a + b  c with a + b + c = 30
If a is odd,then 5a and b + c are odd,so b  c is odd and 5a + b  c is even
If a is even,then 5a and b + c are even,so b  c is even and 5a + b  c is even
From 2 cases,we know that the total score of all participants is always an even number

Phan Thanh Tinh Yesterday at 22:44
1330 = 2 x 5 x 7 x 19 = 2 x 7 x 5 x 19 = 14 x 95
So the grandpa's age and his grandchild's age next year should be 95 and 14 respectively.Then now,the grandpa is 94 and his grandchild is 13
donald trump selected this answer.

Phan Thanh Tinh Yesterday at 22:39
1998 = 2 x 3^{3} x 37,then 1998 has : (1 + 1)(3 + 1)(1 + 1) = 16 (factors)
So x = 16
P/S : 16 is the number of positive factors of 1998,so 1998 has 32 integer factors
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»ﻲ2004#ﻲ« 6 hour before (06:11)
1998 = 2 x 33 x 37,then 1998 has : (1 + 1)(3 + 1)(1 + 1) = 16 (factors)
So x = 16
P/S : 16 is the number of positive factors of 1998,so 1998 has 32 integer factors

Nễu Lả Ánh 23 hour before (12:41)1998 = 2 x 33 x 37,then 1998 has : (1 + 1)(3 + 1)(1 + 1) = 16 (factors)
So x = 16
P/S : 16 is the number of positive factors of 1998,so 1998 has 32 integer factors

Phan Thanh Tinh Yesterday at 22:35
3432 = 2^{3} x 3 x 11 x 13
5460 = 2^{2} x 3 x 5 x 7 x 13
=> GCD (3432 ; 5460) = 2^{2} x 3 x 13 = 156
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»ﻲ2004#ﻲ« 6 hour before (06:12)
3432 = 23 x 3 x 11 x 13
5460 = 22 x 3 x 5 x 7 x 13
=> GCD (3432 ; 5460) = 22 x 3 x 13 = 156

Nễu Lả Ánh 23 hour before (12:41)We have 3432 = 23 x 3 x 11 x 13
5460 = 22 x 3 x 5 x 7 x 13
=> GCD (3432 ; 5460) = 22 x 3 x 13 = 156