The problem of Ulam stability for equations can be stated in terms of how much the
mappings satisfying the equations approximately (in a sense) differ from the exact solutions …

In this article, a new kind of bilateral symmetric additive type functional equation is
introduced. One of the interesting characteristics of the equation is the fact that it is ideal for …

In this paper, we define and investigate the mappings of several variables which are quartic
in each variable. We show that such mappings can be unified as an equation, say the multi …

In this note, the Ulam stability of a general functional equation in several variables is
investigated. It is shown that this equation is Ulam stable in m-Banach spaces. Since a …

In this paper, we first establish a stability result for a functional equation in single variable in
complete b-metric spaces. This result can be applied to prove the stability of various …

For the inner product space, we have Appolonius' identity. From this identity, Park and Th. M.
Rassias induced and investigated the quadratic functional equation of the Apollonius type …

In this article, we study the structure of a multiple variable mapping. Indeed, we reduce the
system of several mixed additive-quadratic equations defining a multivariable mapping to …

In this paper, we study the Ulam stability and hyperstability of two general functional
equations in several variables in 2-Banach spaces. Multi-additive and multi-Jensen …

f (λx)+ f (λy) n0 where n0 is a positive integer with n0= 1, and λ> 0 is a fixed constant. We
prove the Hyers-Ulam stability for the above additive functional equations by using fixed …

In this paper, some remarks on the paper (Ciepliński in Bull Malays Math Sci Soc 46: 62,
2023) are provided. The main results of the manuscript enhance those presented by …