Search

Let A,B be two unital C*-algebras. By using fixed pint methods, we prove that every almost unital almost linear mapping h: A → B which satisfies h(2nuy)= h(2nu)h(y) for all u ∈ U(A), all y ∈ A, and all n=0,1,2, …, is a homomorphism. Also, we establish the generalized Hyers-Ulam-Rassias stability of *-homomorphisms on unital C*-algebras.

In this paper, we achieve the general solution and the generalized Hyres–Ulam–Rassias stability of the following additive–quadratic functional equation $$f (x + ky) + f (x - ky) = f (x + y) + f (x - y) + \frac{2(k + 1)}{k} f (ky) - 2(k + 1)f (y)$$ for fixed integers k with k ≠ 0, ±1 in non-Archimedean spaces.

In this paper, we consider the additive-cubic-quartic functional equation 11[f(x+2y)+f(x−2y)]=44[f(x+y)+f(x−y)]+12f(3y)−48f(2y)+60f(y)−66f(x) and prove the generalized Hyers-Ulam stability of the additive-cubic-quartic functional equation in Banach spaces.