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Prove-that-P-set-of-prime-numbers-is-countable-




Question Number 3551 by prakash jain last updated on 15/Dec/15
Prove that P set of prime numbers is  countable.
ProvethatPsetofprimenumbersiscountable.
Commented by Filup last updated on 15/Dec/15
ah, i understand the question now.  I can′t answer it, though
ah,iunderstandthequestionnow.Icantanswerit,though
Commented by Filup last updated on 15/Dec/15
If by countable, you mean there  is a finite number of primes, then you  are incorrect.    Reason is:  all numbers have prime factors  let n∈Z  ∴n=p_1 ×...×p_k    prime factors  p_i ∈P    n+1≠n     ∴different prime factors.    all primes are prime factors of a number  beacuse p_1 ×...×p_k =n    a single prime is the prime factor of an  infinite amount of numbers
Ifbycountable,youmeanthereisafinitenumberofprimes,thenyouareincorrect.Reasonis:allnumbershaveprimefactorsletnZn=p1××pkprimefactorspiPn+1ndifferentprimefactors.allprimesareprimefactorsofanumberbeacusep1××pk=nasingleprimeistheprimefactorofaninfiniteamountofnumbers
Commented by prakash jain last updated on 15/Dec/15
A countable set may be finite or infinite.  Essentially it means that every element  of set can be associated with natural number.
Acountablesetmaybefiniteorinfinite.Essentiallyitmeansthateveryelementofsetcanbeassociatedwithnaturalnumber.
Commented by prakash jain last updated on 15/Dec/15
P⊂N, since N is countable P is countable.
PN,sinceNiscountablePiscountable.

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