- #1
TyroneTheDino
- 46
- 1
Homework Statement
Express the following statement using only quantifiers. (You may only use the set of Real and Natural Numbers)
1. There is no largest irrational number.
Homework Equations
##\forall=## for all
##\exists##=there exists
The Attempt at a Solution
I express the existence of irrational numbers by saying
##(\exists x \in \Re)(\forall p,q \in\mathbb{N})(\frac{p}{q}\neq x)##
But now saying that x is not the largest irrational number is tricky to me. The book i am using said the answer would look quite complex.
To prove that there is a bigger irrational number I begin by stating that another irrational number exists, and prove that is bigger.
My thinking is that If I write:
##(\forall x \in \Re)(\exists y\in\Re)\wedge(\exists p,q,r,s \in \mathbb{N})\ni[{(\frac{p}{q}\neq x) \wedge(\frac{r}{s}\neq y)}\wedge( y>x)]##
It proves that there is always a bigger irrational number than the one that is being considered, but I'm not completely sure my reasoning makes sense