Abstract
In (Brzdęk and Schwaiger in Aeq Math 92: 975–991,
2018
) solutions of far reaching generalizations of the so-called
radical functional equation
f
(
p
(
π
(
x
)
+
π
(
y
)
)
)
=
f
(
x
)
+
f
(
y
)
have been investigated. These investigations are continued here by analysing the corresponding stability results, which have been the main subject of several recent papers. We propose a very general and uniform approach.