# Math Help - Discrete math question about sets.

1. ## Discrete math question about sets.

little confused as to what this is asking:

Let P be the set of primes and define a relation R from P to N (the natural numbers) by pRn if and only if p|n.

Find all the primes p such that pR126.
Find all n such that 3Rn.

2. Originally Posted by thecleric
Let P be the set of primes and define a relation R from P to N (the natural numbers) by pRn if and only if p|n.
Find all the primes p such that pR126.
Find all n such that 3Rn.
List all prime numbers $p \le \sqrt{126}$.
Which of those divide 126?

3. alternatively write out the prime factor decomposition for 126.
$126=2*3^2*7$ so looks like 2, 3, 7

For the second one its just all natural numbers of the form 3n