Proving 3 Divides at Least One Integer

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In summary, the conversation discusses proving that 3 divides one of the integers n, n+2, or n+4 for any integer n. The solution involves using the division algorithm and examining the remainder when n is divided by 3. The conversation also mentions the importance of showing work in future attempts at solutions.
  • #1
dgentile
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Homework Statement



Prove that 3 divides one of the integers n, n + 2, or n + 4, for any integer n.


Homework Equations





The Attempt at a Solution


 
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  • #2
Try, ok? Any integer n has a remainder of either 0, 1 or 2 when divided by 3. Come on.
 
  • #3
Okay...so what's the formula for proving that true is my question?

Thanks
 
  • #4
Read the forum rules. You are supposed to put something in the "attempt at a solution section". I just gave you a hint. There really is no 'formula'.
 
  • #5
Let n be any such integer. THen by the division algorithm there exist integers q and r such that

[tex] n=3q+r,[/tex]

[tex]n+2=3q_1+r[/tex]

[tex]n+4=3q_2+r[/tex] [tex]0\leq r<3[/tex]

i.e r=0, 1 or 2

Now, say if r=0, what happens? if r=1, what happens? if r=2 what happens?

P.S. This is what Dick said, i just wanted to make a little bit easier on you.
YOu MUST show your work next time.
 

FAQ: Proving 3 Divides at Least One Integer

What does it mean to prove that 3 divides at least one integer?

Proving that 3 divides at least one integer means showing that there exists an integer that can be evenly divided by 3 without leaving a remainder.

Why is proving 3 divides at least one integer important?

This is an important concept in number theory and mathematics in general. It helps us understand divisibility and the properties of integers, and also has applications in various other fields such as cryptography and computer science.

How do you prove that 3 divides at least one integer?

The most common way to prove this is by using a direct proof. This involves assuming that there is no integer that can be divided by 3 without a remainder, and then arriving at a contradiction. This shows that our initial assumption was incorrect and there must be at least one integer that 3 can divide evenly.

Can you give an example of proving 3 divides at least one integer?

Sure, for example, to prove that 3 divides at least one integer in the set {2, 5, 7, 9}, we can use a direct proof. We assume that no integer in this set can be divided by 3 without a remainder. However, 9 can be divided by 3 to give 3 as a quotient. This contradicts our initial assumption, proving that 3 does indeed divide at least one integer in this set.

Are there any other methods for proving 3 divides at least one integer?

Yes, there are several other methods such as using modular arithmetic, proof by contradiction, and proof by contrapositive. However, the direct proof method is the most commonly used and straightforward method for proving this statement.

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