Proving 5 integers to be pairwise relatively prime

In summary: If you show that a factor of one of the numbers is also a factor of another, then that's an immediate contradiction.
  • #1
DerpyPenguin
3
0

Homework Statement


Let n be an integer. Prove that the integers 6n-1, 6n+1, 6n+2, 6n+3, and 6n+5 are pairwise relatively prime.

Homework Equations

The Attempt at a Solution


I tried to prove that the first two integers in the list are relatively prime.

(6n-1)-(6n+1)=1 (trying to eliminate the n variable)
6n-1-6n-1=1
-2=1, which is obviously not true.
Not sure where to go from here. Is there another way to prove that two integers are relatively prime?
 
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  • #2
DerpyPenguin said:

Homework Statement


Let n be an integer. Prove that the integers 6n-1, 6n+1, 6n+2, 6n+3, and 6n+5 are pairwise relatively prime.

Homework Equations

The Attempt at a Solution

[/B]
I tried to prove that the first two integers in the list are relatively prime.

(6n-1)-(6n+1)=1 (trying to eliminate the n variable)
6n-1-6n-1=1
-2=1, which is obviously not true.
Not sure where to go from here. Is there another way to prove that two integers are relatively prime?

You can make at least some progress by noting that ##O = 6n-1## is an odd number, and then arguing that for any odd number ##O##, the pair ##O, O+2## are relatively prime. That also takes care of the pairs ##6n+1, 6n+3##, ##6n+3, 6n+5##. You also have that ##E = 6n+2## is an even number, and can argue that ##E## and ##E+1## are relatively prime, so that takes care of ##6n+2, 6n+3##. That leaves a few more similar pairs to check.

As for showing relative primeness, you just need to show that any factor of one of the numbers fails to be a factor of the other (except for 1, of course). You may be able to do it by contradiction.
 

What does it mean for 5 integers to be pairwise relatively prime?

Two or more integers are considered pairwise relatively prime if they have no common factors other than 1. This means that the greatest common divisor (GCD) of any two of the integers is equal to 1.

How do I prove that 5 integers are pairwise relatively prime?

To prove that 5 integers are pairwise relatively prime, you must show that the GCD of any two of the integers is equal to 1. This can be done by finding the prime factorization of each integer and showing that they do not have any common factors.

Can I use the Euclidean algorithm to prove that 5 integers are pairwise relatively prime?

Yes, the Euclidean algorithm is a commonly used method for proving that integers are relatively prime. It involves finding the GCD of two integers and showing that it is equal to 1.

Do the 5 integers have to be prime for them to be pairwise relatively prime?

No, the 5 integers do not have to be prime for them to be pairwise relatively prime. However, if the 5 integers are all prime, then they will automatically be pairwise relatively prime.

Is it possible for 5 integers to be pairwise relatively prime if they are not all coprime?

No, if the 5 integers are not all coprime (meaning they have a common factor other than 1), then they cannot be pairwise relatively prime. This is because the GCD of any two of the integers would be greater than 1.

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