On the stability of the pexiderized trigonometric functional equation

摘要

The aim of this paper is to investigate the superstability problem of the cosine(d’Alembert), the Wilson, and the sine functional equation from the pexiderized trigonometric functional equation (Tgh) under the condition: |f(x+y)-f(x-y)-2g(x)h(y)|⩽φ(x) or φ(y), and also will investigated the stability of the Jensen type functional equation (Jy) under the condition: |f(x+y)-f(x-y)-2f(y)|⩽φ(x,y).