# Homework Help: Mathmatical proofs help please

1. Dec 4, 2011

### sphelan08

1. Must two uncountable sets have the same cardinality?
a countable union of countable sets is countable.
Is a finite set necessarily countable?
If the union of A and B is infinite, then A or B must be inifinte

2. Just use definitions of Uncountable, Countable, finite, and infinite, and cardinality to do these proofs.

2. Dec 4, 2011