The general form of a first-order partial differential equation is F(x, y, z, p, q) = 0, where p and q are the partial derivatives of the dependent variable z with respect to x and y, respectively.

Separation of Variables is a powerful technique for solving linear partial differential equations with constant coefficients. It involves finding solutions that are products of functions, each depending on a single independent variable.

The fundamental solution of a linear partial differential equation is a solution that satisfies the equation at a single point. It is also known as the Green's function.

The Cauchy-Kovalevskaya Theorem provides conditions under which a partial differential equation has a unique solution in a neighborhood of a given point.

The method of characteristics is a powerful technique for solving nonlinear partial differential equations. It involves finding curves along which the solution is constant.

The Heat Equation is a partial differential equation that describes the diffusion of heat in a medium. It is a second-order linear partial differential equation.

The general form of a second-order linear partial differential equation is Au + Bv + Cw + Du + Ev + Fw + G = 0, where u, v, and w are the dependent variables, and A, B, C, D, E, F, and G are the coefficients.

Separation of Variables is a powerful technique for solving the wave equation. It involves finding solutions that are products of functions, each depending on a single independent variable.

The Laplace transform is a powerful tool for solving partial differential equations with boundary conditions. It involves transforming the partial differential equation into an algebraic equation, which can then be solved using standard techniques.

The Wave Equation is a partial differential equation that describes the propagation of sound waves in a medium. It is a second-order linear partial differential equation.

The method of undetermined coefficients is a powerful technique for solving linear partial differential equations with constant coefficients. It involves guessing a solution of the form $$y = e^{mx + ny}$$ and then determining the values of m and n that satisfy the equation.

Laplace's Equation is a partial differential equation that governs the steady-state temperature distribution in a two-dimensional region. It is a second-order linear partial differential equation.

The method of weighted residuals is a powerful technique for solving partial differential equations with variable coefficients. It involves approximating the solution of the equation by a linear combination of basis functions and then minimizing the residual.

The Navier-Stokes Equations are a system of partial differential equations that govern the flow of an incompressible fluid. They are a set of second-order nonlinear partial differential equations.

The method of finite differences is a powerful technique for solving partial differential equations with variable coefficients. It involves approximating the derivatives in the equation by finite differences and then solving the resulting system of algebraic equations.