The Stability of an Additive-Quartic FunctionalEquation in Quasi-β-Normed Spaces with the Fixed Point Alternative

Anurak Thanyacharoen, Wutiphol Sintunavarat


In this paper, the generalized Hyers-Ulam stability for the following additive-quartic functional equation    \begin{align*}        f(x+3y)+f(x-3y)+f(x+2y)+f(x&-2y)+ 22f(x)+24f(y)\\&=13[f(x+y)+f(x-y)]+12f(2y)    \end{align*}is determined, where $f$ maps from a normed space to a quasi-$\beta$-Banach space.


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