Stability of a k Cubic Functional Equation in Quasi - β Normed Spaces: Direct and Fixed Point Methods
Matina J. Rassias
Department of Statistical Science, University College London, 1-19 Torrington Place, #140, London, WC1E 7HB, UK.
M. Arunkumar *
Department of Mathematics, Government Arts College, Tiruvannamalai - 606 603, Tamil Nadu, India.
E. Sathya
Department of Mathematics, Government Arts College, Tiruvannamalai - 606 603, Tamil Nadu, India.
*Author to whom correspondence should be addressed.
Abstract
In this paper, we introduce and investigate the Hyers - Ulam stability of a k cubic functional
equation of the form
for 
in quasi - 
normed spaces using both direct and fixed point methods.
Keywords: Cubic functional equations, Generalized Ulam - Hyers stability, quasi - normed spaces, fixed point method