C Park, J Senasukh - Asian-European Journal of …, 2023 - search.ebscohost.com
In this paper, we study an (A, Q)-functional equation f (x+ y, z+ w)+ f (x+ y, z− w)+ f (x− y, z+
w)+ f (x− y, z− w)= 4 f (x, z)+ 4 f (x, w) in a Banach space and determine its general solutions …