Would it be wrong to argue that if one considers a countable set $A$ and a real function $f:\mathbb{R}\to\mathbb{R}$, then the range of $f$ on $A$, that is the set $f(A)=\{f(a)\mid a\in A\}$, is countable?
Asked
Active
Viewed 31 times
0
-
1it's obviously correct. – Walace May 07 '20 at 08:13
-
Or this: https://math.stackexchange.com/q/144751. – Martin R May 07 '20 at 08:18