thrm: \(\mathbb{N} \times \mathbb{N}\) is Countable
Countable, then S is countable
1-\(1,1)\
2-\(2,1)\
3-\(1,2)\
4-\(1,3)\
is Q countable? Show it (draw a picture)
test Prep
5.1 Rational numbers
Prove the relation \((a,b) \sim (c,d)\) defined by \(a \cdot d = b \cdot c\) is an e