Generalized Hyers-Ulam Stability for a General Mixed Functional Equation in Quasi-β-normed Spaces

In this paper, we establish the general solution and investigate the generalized Hyers-Ulam stability of the following mixed additive and quadratic functional equation f(λx + y) + f(λ - y) = f(x + y) + f(x - y) + (λ - 1)[(λ + 2)f(x) + λf(-x)], (λ ε ℕ,λ ≠ 1) in quasi-β-normed spaces. © 2010 Springer Basel AG