title: A general theorem on the stability of a class of functional equations including quadratic-additive functional equations.
abstract: We prove a general stability theorem of an n-dimensional quadratic-additive type functional equation [Formula: see text]by applying the direct method.
authors.affiliation: Department of Mathematics Education, Gongju National University of Education, Gongju, 32553 Republic of Korea.
authors.forename: Yang-Hi
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Mathematics Section, College of Science and Technology, Hongik University, Sejong, 30016 Republic of Korea.
authors.forename: Soon-Mo
authors.initials: SM
authors.lastname: Jung
keywords: Direct method; Functional equation; Generalized Hyers-Ulam stability; n-dimensional quadratic-additive type functional equation