The Stability of an Additive-Quartic Functional Equation in Quasi-$\beta$-Normed Spaces with the Fixed Point Alternative
Anurak Thanyacharoen, Wutiphol Sintunavarat
Keywords:
quasi-β-normed spaces, additive functional equations, quartic functional equationsAbstract
The aim of this paper is to use the fixed point alternative for investigating the generalized Hyers-Ulam stability for the following additive-quartic functional equation
$$f(x+3y)+f(x-3y)+f(x+2y)+f(x-2y)+ 22f(x)+24f(y) =13[f(x+y)+f(x-y)]+12f(2y),$$
where $f$ maps from a normed space to a quasi-$\beta$-Banach space.