STABILITY FOR AN n-DIMENSIONAL FUNCTIONAL EQUATION OF QUADRATIC-ADDITIVE TYPE WITH THE FIXED POINT APPROACH
In this paper, we investigate the stability of a functional equation Sigma(1 <=tau,j <= n,i not equal j) [f(x(i) + x(j)) + f (x(i) - x(j))] - (n - 1) Sigma(f)(j=1)(2x(j)) = 0 by using the fixed point methd in the sense of Cadariu and Radu.
stability fixed point method n-dimensional quadratic-additive type functional equation