Generalized Hyers-Ulam stability of a mixed type functional equation
Summary: We investigate the stability of a functional equation \(f(x+y+z)+f(x-y+z)+f(x+y-z)+f(-x+y+z)=3f(x)+f(-x)+3f(y)+f(-y)+3f(z)+f(-z)\) by applying the direct method in the sense of Hyers and Ulam.
scientific article; zbMATH DE number 6306856