Keyword: «second-order equations»

In this article I will give a general overview of differential equations with two variables, the theorems given to it, and various examples of lemmas based on the equation. I will focus on hyperbolic, parabolic, and elliptic types of solutions of differential equations. Canonical types of equations with constant coefficients and creation (reduction) of the general problem were mentioned, and the conclusion was drawn by connecting them with examples.