• Journal of applied mathematics & informatics
• /
• v.36 no.1_2
• /
• pp.1-14
• /
• 2018

In this paper, we prove the existence, uniqueness and stability of solution for some nonlinear functional-integral equations by using generalized coupled Lipschitz condition. We prove a fixed point theorem to obtain the mentioned aim in Banach space $X=C([a,b],{\mathbb{R}})$. As application we study some volterra integral equations with linear, nonlinear and single kernel.

• Kyungpook Mathematical Journal
• /
• v.50 no.4
• /
• pp.557-564
• /
• 2010

By using an idea of C$\u{a}$dariu and Radu [4], we prove the generalized Hyers-Ulam stability of the functional equation f(x + y,z - w) + f(x - y,z + w) = 2f(x, z) + 2f(y, w). The quadratic form $f\;:\;\mathbb{R}\;{\times}\;\mathbb{R}{\rightarrow}\mathbb{R}$ given by f(x, y) = $ax^2\;+\;by^2$ is a solution of the above functional equation.

• Bulletin of the Korean Mathematical Society
• /
• v.41 no.2
• /
• pp.347-357
• /
• 2004

In this note we will find out the general solution and investigate the generalized Hyers-Ulam-Rassias stability for the cubic functional equation f(3$\chi$+y) + f($3\chi$-y) = $3f(\chi$+ y) + $3f(\chi$-y) + ($48f(\chi)$ on abelian groups.

• Korean Journal of Mathematics
• /
• v.16 no.2
• /
• pp.205-214
• /
• 2008

In this paper, we prove the generalized Hyers-Ulam stability of a Cauchy-Jensen functional equation $2f(x+y,\frac{z+w}{2})=f(x,z)+f(x,w)+f(y,z)+f(y,w)$ in the spirit of $P.G{\breve{a}}vruta$.

• Journal of applied mathematics & informatics
• /
• v.15 no.1_2
• /
• pp.343-361
• /
• 2004

We prove the generalized Hyers-Ulam-Rassias stability of cyclic functional equations in Banach modules over a unital $C^{*}$-algebra. It is applied to show the stability of algebra homomorphisms between Banach algebras associated with cyclic functional equations in Banach algebras.

• Journal of applied mathematics & informatics
• /
• v.15 no.1_2
• /
• pp.467-474
• /
• 2004

We prove the generalized Hyers-Ulam-Rassias stability of a partitioned functional equation. It is applied to show the stability of algebra homomorphisms between Banach algebras associated with partitioned functional equations in Banach algebras.

• Journal of applied mathematics & informatics
• /
• v.22 no.1_2
• /
• pp.517-522
• /
• 2006

In this paper, we obtain the general solution and the generalized Hyers-Ulam stability of the multi-additive functional equation $f(x1+x2,y1+y2,z1+z2)={\Sigma}_{1{\le}i,j,k{\le}2}\;f(x1,yj,zk)$.

• Journal of applied mathematics & informatics
• /
• v.18 no.1_2
• /
• pp.563-572
• /
• 2005

In this paper, we obtain the general solution and the generalized Hyers-Ulam stability of the additive-quadratic functional equation f(x + y, z + w) + f(x + y, z - w) = 2f(x, z)+2f(x, w)+2f(y, z)+2f(y, w).

• Kyungpook Mathematical Journal
• /
• v.55 no.2
• /
• pp.313-326
• /
• 2015

In this paper, we present a fixed point method to prove generalized Hyers-Ulam stability of the systems of quadratic-cubic functional equations with constant coefficients in modular spaces.

• Journal of the Chungcheong Mathematical Society
• /
• v.25 no.2
• /
• pp.159-170
• /
• 2012

In this paper, we investigate the stability of a bi-Jensen functional equation $2{f}(\frac{x+y}{2},\;z)-f(x,\;z)-f(y,\;z)=0$, $2{f}(x,\;\frac{y+z}{2})-f(x,\;y)-f(x,\;z)=0$ in the spirit of P.G$\breve{a}$vruta.