This is an exercise in Marcus. I think what Marcus means is that $m$ contains at least an odd power of prime.
$Q(m^{1/4})/Q$ is degree 4 extension where $m$ is not a square.
For $m=-4$, $Q(m^{1/4})=Q(i)$.
$\textbf{Q:}$ Does he mean that $m$ contains at least an odd power of prime or he means that $m>0$?