Resumen de Remarks on the stability of Drygas' equation and the Pexider-quadratic equation
Dilian Yang
In this note, we improve the results proved by S.-M. Jung [8], and S.-M. Jung and P. K. Sahoo [9] on the stability of the Pexider-quadratic functional equation and Drygas equation, respectively. We give sharper bounds on more general settings by making use of different and easier ways. An example is also given to illustrate that the quadratic equation (and so the Pexider-quadratic equation) is not stable on the free group generated by two elements.
