In scholastic philosophy, the aevum (also called aeviternity) is the temporal mode of existence experienced by angels and by the saints in heaven. In some ways, it is a state that logically lies between the eternity (timelessness) of God and the temporal experience of material beings. It is sometimes referred to as "improper eternity". (Wikipedia).

The method of determining eigenvalues as part of calculating the sets of solutions to a linear system of ordinary first-order differential equations.

From playlist A Second Course in Differential Equations

The Difference Between an Expression and an Equation

This video explains the difference between an expression and an equation. Site: http://mathispower4u.com Blog: http://mathispower4u.wordpress.com

From playlist Introduction to Linear Equations in One Variable

(0.3.101) Exercise 0.3.101: Classifying Differential Equations

This video explains how to classify differential equations based upon their properties https://mathispower4u.com

From playlist Differential Equations: Complete Set of Course Videos

Linear Algebra: We introduce eigenvalues and eigenvectors by considering the equation Av=cv. After considering the geometric content of this equation, we provide a procedure for finding eigenvalues and eigenvectors and apply it to the matrix A = [ 1 1 0 / 1 0 1/ 0 1 1 ].

From playlist MathDoctorBob: Linear Algebra I: From Linear Equations to Eigenspaces | CosmoLearning.org Mathematics

Changing notation with complex eigenvalues.

From playlist A Second Course in Differential Equations

C07 Homogeneous linear differential equations with constant coefficients

An explanation of the method that will be used to solve for higher-order, linear, homogeneous ODE's with constant coefficients. Using the auxiliary equation and its roots.

From playlist Differential Equations

Math 060 Linear Algebra 01 090514: Systems of Linear Equations; Matrices

1.1 Introduction: systems of linear equations. "Legal" operations (that result in equivalent systems, i.e., systems with the same solution set). Row echelon form, lead variables, free variables. Definition of a matrix; matrix addition, scalar multiplication, additive inverses.

From playlist Course 4: Linear Algebra

From playlist Tutorial 8

Linear Algebra: Continuing with function properties of linear transformations, we recall the definition of an onto function and give a rule for onto linear transformations.

From playlist MathDoctorBob: Linear Algebra I: From Linear Equations to Eigenspaces | CosmoLearning.org Mathematics

Linear Algebra - Lecture 33 - Eigenvectors and Eigenvalues

In this lecture, we define eigenvectors and eigenvalues of a square matrix. We also prove a couple of useful theorems related to these concepts.

From playlist Linear Algebra Lectures