Prime Numbers Flashcards
What is Lemma 3.1?
Let a, b be integers
1. If p is irreducible, either p divides a or a and p are coprime
2. If p is prime then it is irreducible
3. If p is irreducible then it is also prime
What does irreducible mean?
It means that the only divisors of p are 1 and p
What does prime mean?
P is said to be prime if for all integers a and b, if p|ab then
p|a or p|b
What is an integer that is not irreducible called?
Composite and it has the form n=ab
What is corollary 3.2?
If p is prime and divides a1…ak, then p divides ai for some I.
What is theorem 3.3 (The Fundamental theorem of Arithmetic)?
Each integer n>1 has a prime-power factorisation
n=p1^e1…pk^ek
Where p1…pk are distinct primes and e1…ek are positive integers, this factorisation is unique, apart from permutations of the factors
What is corollary 3.6?
If a positive integer m is not a perfect square then root(m) is irrational
What is theorem 3.7?
There are infinitely many primes
What is corollary 3.9?
The n-th prime pn satisfies pn <= 2^(2n-1) for all n>= 1