A fixed-point approach to the stability of a functional equation on quadratic forms
نویسندگان
چکیده
* Correspondence: [email protected] Department of Mathematics Education, College of Education, Mokwon University, Daejeon, 302729, Korea Full list of author information is available at the end of the article Abstract Using the fixed-point method, 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 : R × R ® R given by f(x, y) = ax + bxy + cy is a solution of the above functional equation.
منابع مشابه
A fixed point approach to the stability of additive-quadratic-quartic functional equations
In this article, we introduce a class of the generalized mixed additive, quadratic and quartic functional equations and obtain their common solutions. We also investigate the stability of such modified functional equations in the non-Archimedean normed spaces by a fixed point method.
متن کاملApproximate a quadratic mapping in multi-Banach spaces, a fixed point approach
Using the fixed point method, we prove the generalized Hyers-Ulam-Rassias stability of the following functional equation in multi-Banach spaces:begin{equation} sum_{ j = 1}^{n}fBig(-2 x_{j} + sum_{ i = 1, ineq j}^{n} x_{i}Big) =(n-6) fBig(sum_{ i = 1}^{n} x_{i}Big) + 9 sum_{ i = 1}^{n}f(x_{i}).end{equation}
متن کاملQuadratic $alpha$-functional equations
In this paper, we solve the quadratic $alpha$-functional equations $2f(x) + 2f(y) = f(x + y) + alpha^{-2}f(alpha(x-y)); (0.1)$ where $alpha$ is a fixed non-Archimedean number with $alpha^{-2}neq 3$. Using the fixed point method and the direct method, we prove the Hyers-Ulam stability of the quadratic $alpha$-functional equation (0.1) in non-Archimedean Banach spaces.
متن کاملA fixed point approach to the Hyers-Ulam stability of an $AQ$ functional equation in probabilistic modular spaces
In this paper, we prove the Hyers-Ulam stability in$beta$-homogeneous probabilistic modular spaces via fixed point method for the 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 $kneq 0,pm1.$
متن کاملHyperstability of some functional equation on restricted domain: direct and fixed point methods
The study of stability problems of functional equations was motivated by a question of S.M. Ulam asked in 1940. The first result giving answer to this question is due to D.H. Hyers. Subsequently, his result was extended and generalized in several ways.We prove some hyperstability results for the equation g(ax+by)+g(cx+dy)=Ag(x)+Bg(y)on restricted domain. Namely, we show, under some weak natural...
متن کاملA FIXED POINT APPROACH TO THE INTUITIONISTIC FUZZY STABILITY OF QUINTIC AND SEXTIC FUNCTIONAL EQUATIONS
The fixed point alternative methods are implemented to giveHyers-Ulam stability for the quintic functional equation $ f(x+3y)- 5f(x+2y) + 10 f(x+y)- 10f(x)+ 5f(x-y) - f(x-2y) = 120f(y)$ and thesextic functional equation $f(x+3y) - 6f(x+2y) + 15 f(x+y)- 20f(x)+15f(x-y) - 6f(x-2y)+f(x-3y) = 720f(y)$ in the setting ofintuitionistic fuzzy normed spaces (IFN-spaces). This methodintroduces a met...
متن کامل