NOTES ON THE SUPERSTABILITY OF D'ALEMBERT TYPE FUNCTIONAL EQUATIONS

Notes on the Superstability of D’alembert Type Functional Equations

In this paper we will investigate the superstability of the generalized d’Alembert type functional equations Pm i=1 f(x + σ i(y)) = kg(x)f(y) and Pm i=1 f(x + σ i(y)) = kf(x)g(y).

the effect of functional/notional approach on the proficiency level of efl learners and its evaluation through functional test

in fact, this study focused on the following questions: 1. is there any difference between the effect of functional/notional approach and the structural approaches to language teaching on the proficiency test of efl learners? 2. can a rather innovative language test referred to as "functional test" ge devised so so to measure the proficiency test of efl learners, and thus be as much reliable an...

On the Superstability of the Pexider Type Trigonometric Functional Equation

We will investigate the superstability of the hyperbolic trigonometric functional equation from the following functional equations: fx y ± gx − y λfxgy andfx y ± gx − y λgxfy, which can be considered the mixed functional equations of the sine function and cosine function, the hyperbolic sine function and hyperbolic cosine function, and the exponential functions, respectively.

Superstability of Some Pexider-Type Functional Equation

The Superstability of the Pexider Type Trigonometric Functional Equation

The aim of this paper is to investigate the stability problem for the Pexider type (hyperbolic) trigonometric functional equation f(x + y) + f(x + σy) = λg(x)h(y) under the conditions : |f(x + y) + f(x + σy)− λg(x)h(y)| ≤ φ(x), φ(y), and min{φ(x), φ(y)}. As a consequence, we have generalized the results of stability for the cosine(d’Alembert), sine, and the Wilson functional equations by J. Bak...