213 ∀a,b∈ℚ and a≠b, ∃c in (a,b) and c∉ℚ
by EngliSea on 2020-07-16
ᐥBetween any two distinct rationals there is an irrational.ᐥ

For any two rationals, a and b,  such that a<b,
0 < b−a
0 < (√2/2)·(b−a)
a < a+(√2/2)·(b−a)
= a+√2·((b−a)/2)
┆√2/2 < 1┆
< a+(b−a)
= b
a+√2·((b−a)/2) is irrational and lies between two rationals.