Question

Let $A=\{9,10,11,12,13\}$ and $f:A\to N$ be defined by $f\left(n\right)$= the largest prime factor of $n$. Find the range of $f$

Answer 1

$A=\{9,10,11,12,13\}$

$f\left(9\right)=3f\left(10\right)=5f\left(11\right)=11f\left(12\right)=3f\left(13\right)=13$

So the range is $\{3,5,11,13\}$