Journal of Inequalities and Applications
Volume 2009 (2009), Article ID 868423, 14 pages
doi:10.1155/2009/868423
Research Article

Quadratic-Quartic Functional Equations in RN-Spaces

M. Eshaghi Gordji,1 M. Bavand Savadkouhi,1 and Choonkil Park2

1Department of Mathematics, Semnan University, P.O. Box 35195-363, Semnan, Iran
2Department of Mathematics, Hanyang University, Seoul 133-791, South Korea

Received 20 July 2009; Accepted 3 November 2009

Academic Editor: Andrea Laforgia

Copyright © 2009 M. Eshaghi Gordji 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 obtain the general solution and the stability result for the following functional equation in random normed spaces (in the sense of Sherstnev) under arbitrary t-norms f(2x+y)+f(2x−y)=4[f(x+y)+f(x−y)]+2[f(2x)−4f(x)]−6f(y).