Journal of Inequalities and Applications
Volume 2010 (2010), Article ID 839639, 18 pages
doi:10.1155/2010/839639
Research Article

A Fixed Point Approach to the Stability of Pexider Quadratic Functional Equation with Involution

M. M. Pourpasha,1 J. M. Rassias,2 R. Saadati,3 and S. M. Vaezpour3

1Department of Mathematics, Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran
2Section of Mathematics and Informatics, Pedagogical Department, National and Kapodistrian University of Athens, 4, Agamemnonos St., Aghia Paraskevi, Athens 15342, Greece
3Department of Mathematics, Amirkabir University of Technology, Hafez Avenue, P. O. Box 15914, Tehran, Iran

Received 10 May 2010; Revised 13 July 2010; Accepted 31 July 2010

Academic Editor: S. Reich

Copyright © 2010 M. M. Pourpasha et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We apply the fixed point method to investigate the Hyers-Ulam stability of the Pexider functional equation f(x+y)+g(x+σ(y))=h(x)+k(y), for all x,y∈E, where E is a normed space and σ:E→E is an involution.