Functional equation and its stability have been a rapidly developing area and a number of research papers are being published on the same. Inspite of the growing interest, all these publications lack a proper methodology and go only by a trial and error method to form a various type of functional equations. This chapter explains a possible method to model various types of functional equations like additive, quadratic and mixed type of additive and quadratic using eigenvalues and eigenvectors of newly established kn — 2 scalar matrices with suitable numerical examples. The study of functional equations is a contemporary area of mathematics that provides a powerful approach to working with important concepts and relationships in analysis and algebra such as symmetry, linearity and equivalence. The chapter proposes a new method to model additive, quadratic and mixed type functional equations through eigenvalues and eigenvectors of kn — 2 matrices.