APPROXIMATE QUADRATIC FUNCTIONAL EQUATION IN FELBIN'S TYPE NORMED LINEAR SPACES

Abstract

In this paper, we prove the generalized Hyers-Ulam-Rassias stability ofquadratic functional equation in Felbin's type normed linear spaces byusing the direct and fixed point methods. The concept of Hyers-UlamRassias stability originated from Th. M. Rassias' stability theorem thatappeared in his paper: On the stability of the linear mapping in Banachspaces, Proc. Amer. Math. Soc. 72 (1978), 297-300.