A Fixed Point Approach to the Stability of the Cauchy Additive and Quadratic Type Functional Equation

Abstract

We investigate the stability of the functional equation $\mathrm{2f}(x+y)+f(x-y)+f(y-x)-\mathrm{3f}\left(x\right)-f(-x)-\mathrm{3f}\left(y\right)-f(-y)=0$ by using the fixed point theory in the sense of Cadariu and Radu.