scholarly journals A Fixed Point Approach to the Stability of Quadratic Equations in Quasi Normed Spaces

2009 ◽  
Vol 49 (4) ◽  
pp. 691-700
Author(s):  
Alireza Kamel Mirmostafaee
2016 ◽  
pp. 4430-4436
Author(s):  
Seong Sik Kim ◽  
Ga Ya Kim

In this paper, we prove the generalized Hyers-Ulam stability of a general k-quadratic Euler-Lagrange functional equation:for any fixed positive integer in intuitionistic fuzzy normed spaces using a fixed point method.


2010 ◽  
Vol 2010 (1) ◽  
pp. 423231 ◽  
Author(s):  
TianZhou Xu ◽  
JohnMichael Rassias ◽  
MatinaJohn Rassias ◽  
WanXin Xu

2010 ◽  
Vol 2010 ◽  
pp. 1-24 ◽  
Author(s):  
Tian Zhou Xu ◽  
John Michael Rassias ◽  
Wan Xin Xu

Using the fixed point methods, we prove the generalized Hyers-Ulam stability of the general mixed additive-quadratic-cubic-quartic functional equationf(x+ky)+f(x−ky)=k2f(x+y)+k2f(x−y)+2(1−k2)f(x)+((k4−k2)/12)[f(2y)+f(−2y)−4f(y)−4f(−y)]for a fixed integerkwithk≠0,±1 in non-Archimedean normed spaces.


Filomat ◽  
2017 ◽  
Vol 31 (15) ◽  
pp. 4933-4944
Author(s):  
Dongseung Kang ◽  
Heejeong Koh

We obtain a general solution of the sextic functional equation f (ax+by)+ f (ax-by)+ f (bx+ay)+ f (bx-ay) = (ab)2(a2 + b2)[f(x+y)+f(x-y)] + 2(a2-b2)(a4-b4)[f(x)+f(y)] and investigate the stability of sextic Lie *-derivations associated with the given functional equation via fixed point method. Also, we present a counterexample for a single case.


2013 ◽  
Vol 29 (1) ◽  
pp. 125-132
Author(s):  
CLAUDIA ZAHARIA ◽  
◽  
DOREL MIHET ◽  

We establish stability results concerning the additive and quadratic functional equations in complete Menger ϕ-normed spaces by using fixed point theory. As particular cases, some theorems regarding the stability of functional equations in β - normed and quasi-normed spaces are obtained.


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