Lee, JRPark, CAlaca, CShin, DY2024-07-182024-07-181521-13981572-9206http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/8568Using the fixed point method, we prove the Hyers-Ulam stability of the orthogonally additive-quadratic functional equation 2f (x+y/2) + 2f (x-y/2) = 3/2 f(x) - 1/2 f(y) + 1/2f(-y) (0.1) for all x, y with x perpendicular to y, in non-Archimedean Banach spaces. Here perpendicular to is the orthogonality in the sense of Ratz.EnglishNORMED SPACESBANACH-SPACESTHEOREMArticle