Solution and Stability of a Mixed Type Cubic and Quartic Functional Equation in Quasi-Banach Spaces

Abstract

We obtain the general solution and the generalized Ulam-Hyers stability of the mixed type cubic and quartic functional equation $f\left(x+2y\right)+f\left(x-2y\right)=4\left(f\left(x+y\right)+f\left(x-y\right)\right)-24f\left(y\right)-6f\left(x\right)+3f\left(2y\right)$ in quasi-Banach spaces.