The ε-Hyperstability of an Euler-Lagrange Type Quadratic Functional Equation in Banach Spaces
Mohamed Sirouni *
Faculty of Sciences, Department of Mathematics, Ibn Tofail University, BP:14000, Kenitra, Morocco.
Samir Kabbaj
Faculty of Sciences, Department of Mathematics, Ibn Tofail University, BP:14000, Kenitra, Morocco.
*Author to whom correspondence should be addressed.
Abstract
The main goal of this paper is the investigation of the ε-hyperstability of an Euler-Lagrange type quadratic functional equation
f(x + y) +1/2[f(x - y) + f(y - x)] = 2f(y) + 2f(x)
in the class of functions from an abelian group into a Banach space.
Keywords: Quadratic functional equation, stability, hyperstability, banach space.