# All Questions

##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:58-
\(2015=5\cdot13\cdot31\)

So their sum is: 5 + 13 + 31 = 49

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##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:57-
It takes \(\dfrac{35}{30}=\dfrac{7}{6}\left(h\right)=70'\) to drive all this distance at 30mi/h

It takes \(\dfrac{25}{30}=\dfrac{5}{6}\left(h\right)=50'\)to drive all this distance at 25mi/h

So drive at 30mi/h is takes fewer than 25mi/h is: 70' - 50' = 20'

Answer: 20 minutes

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##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:57##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:56-
Nguyễn Mạnh Hùng 02/07/2018 at 08:42
A package of Koka-Kola is: 12 x 8 = 96 (ounces)

A package of Pepsy-Kola is: 16 x 6 = 96 (ounces)

=> The absolute different is 0, not right yet ^^

Lê Quốc Trần Anh selected this answer.

##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:56-
Nguyễn Mạnh Hùng 02/07/2018 at 08:51
Call the radius is r, the height is h

We have:

Cylinder 1 has the volume is: \(\left(2r\right)^2.\Pi.h=\Pi.4r^2.h\)

Cylinder 2 has the volume is: \(r^2.\Pi.k.h\)

We have: \(\dfrac{C1}{C2}=1\)

\(\Rightarrow\dfrac{4r^2.\Pi.h}{r^2.\Pi.k.h}=1\)

\(\Rightarrow\dfrac{4}{k}=1\)

\(\Rightarrow k=4\)

Lê Quốc Trần Anh selected this answer.

##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:55-
If A true

=> B false and C true

=> D false and A false (Contrary to suppose)

So A false

=> C is true statement.

Lê Quốc Trần Anh selected this answer.

##### Lê Quốc Trần Anh Coodinator

02/07/2018 at 02:54-
a # b = a + 2b

=> 3 # 4 = 3 + 2.4 = 3 + 8 = 11

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##### Huỳnh Anh Phương

02/07/2018 at 02:01-
Hi Phương, you should use "latex" or "formula" to express your question.

Your question should be presented as: \(x! = 1+2+x\).

About your question, I think \(x \) should be a natural number.

After some transformation, we get:

\(x.[(x-1)!-1]=3\)

So \(x\) is a divisor of 3. We can easily find \(x=3.\)

Huỳnh Anh Phương selected this answer.