ABSTRACT
The subject functional equations generalizes a modern branch of mathematics (see, e.g., [55]). During 1747–1750, J. d’Alembert published three papers and these three papers were the first on functional equations. Many mathematicians like N. H. Abel, J. Bolyai, A. L. Cauchy, J. d’Alembert, L. Euler, M. Frechat, C. F. Gauss, J. L. W. V. Jensen, A. N. Kolmogorov, N. I. Lobacevskii, J. V. Pexider and S. D. Poisson have studied functional equations because of their apparent simplicity and harmonic nature.
