Welcome to Differential Equations!

Ordinary Differential Equations | The Cheat Sheet | Partial Differential Equations


Background Information

Before we get started, it is best to know a few things that will helps deal with theses differential equations. These concepts are quickly covered in class though not guranteed, so it is best to discuss it here first.


Linearity & Principle of Superposition

Linearity and principle of superposition are two concepts that is thrown around in differential equation and physics and so this video will explain what they are and give you a better understanding about them.



Ordinary Differential Equations

Solving ODEs | Linear Systems of Differential Equations


Solving Ordinary Differential Equations

Lecture | Homogeneous Equations with Constant Coefficient

Solving differential equations is not as hard as you think. This lecture will show you how to solve and ODE using the algebra you learned way back... the quadratic equation ;-;This lecture will discuss about using the characteristic equation to solve for homogeneous equations with constant coefficients.

Example | Solving Homogeneous Equations Using the Characteristic Equation

Using what was discussed in the previous video, we will solve ODEs using the characteristic equation.

Example | Initial Value Problems with Constant Coefficient

Nothing new here, other than the specific solution of homogeneous ODEs with constant coefficient.

Example | Initial Value Problems with Constant Coefficient (Part 2)

Some more examples with finding our c1 and c2 :D

Lecture | Method of Undetermined Coefficients

We know how to solve for ODE's that homogeneous... what if they are nonhomogeneous?? Hmmmm it turns out that its just like solving for homogeneous ODEs (mostly) but with extra steps :D

Example | Finding the Particular Solution for a Nonhomogenous ODE

Solving nonhomogenenous equations is the same as solving a homogeneous equation, but it has one extra step which is what the video is about.

Example | Initial Value Problems for Nonhomogeneous Equations

Now it's time to find the specific solution for a nonhomogeneous equation.

Example | Initial Value Problem for Nonhomogeneous Equations (Part 2)

Same thing as the previous examples except this is a bit more challenging.

Lecture | Cauchy-Euler Method

Even though this is a "new" method, we will still be using the other 2 methods that were taught. What makes this new is the type of ODE that we will be looking at!

Example | Using the Cauchy-Euler Method

These examples about to "catch these hands." Solving homogeneous Cauchy-Euler equations will be a breeze as you will see by the length of the video lol.

Example | Particular Solution Using the Cauchy-Euler Method

We all know the homogeneous ODEs are the easiest, so let's add a little spice and do some nonhomogeneous ODEs :D

Lecture/Example Hybrid | Two-function substitution Method

In this video we will discuss another method to solve ODEs which involves guessing our solution to being the product of 2 functions.

Lecture/Example Hybrid | Transformation Method

In this example/lecture hybrid I will discuss about a new method of solving an ODE that takes in the same form as the previous lecture/example hybrid and do one example that uses this method.

Linear Systems of Differential Equations

Lecture | Systems of Differential Equations

Systems of equations?!?! This isn't linear algebra... well... there are some things in linear algebra that can be used in ODE such as having a linear system of differential equations.

Example | Converting Diferential Equations to First-Order Systems

Baby steps. Starting small by creating first-order systems before we start solving these systems :)

Example | Solving 2-D Systems of Differential Equations

Still taking baby steps as we solve a linear system by converting it into a 2nd order differential equation, which we know how to solve so it shouldn't be too hard.

Example | Using the Wronskian Determinant

Skipping massive steps, this video will show you how to check if the set of solutions are linearly independent.

Lecture | Solving Linear Systems of ODEs

Ayo?!?! I thought we did this already?!?!?! Well... yes.... kind of... This lecture will show the holistic version of solving linear systems of differential equations and not just the 2-by-2 that we previously discussed.

Example | Solving Systems of Linear Equations (Easy)

Well... they are easier than the other types of systems. We are going to start solving basic linear ODE systems before we get into the more challenging ones.

Example | General Way for Systems of ODEs with Defective Eigenvalues

Before we get into actually solving systems containing defective eigenvalues, we will first see how we write the genereal solution for such system to get a sense of what we are dealing with.

Example | Solving Systems of ODEs Containing Defective Eigenvalues

Hopefully you saw the previous video, if not its up there ^^ >:( Now we are going ot solve a system of ODE that has defective eigenvalues and paint a clear picture on how the solutions are written.

ODE Proof | Obtaining Real Solutions for the Complex Case

Taking a step back in examples, it is best to understand why is it that we can obtain real solutions to a complex case of defective eigenvalues. One reason is the eigenvalue must have a conjugate pair. Additionally, this will cover the general steps to solving these types of systems.

Example | Solving Systems of ODE with Complex Eigenvalues

Now that we know where the solutions comes from, we are now going to solve a system of ODEs that containes complex eigenvalues!


The Cheat Sheet

Are we conducting academic dishonesty here?!?! Of course not!! This series will help you conduct a universal cheat sheet for your PDE exam (assuming they allow you to have one). This section will focus on showing the work on certain problems that frequently show up when solving PDEs. Some of this can also help you in your ODE class too ;)


Faster Way to Solve Second-order Homogeneous Differential Equations

In this first video, I will be showing you a much faster way to solve 2nd order ODE without using the characteristic equation ;-;

Faster Way of the Cauchy-Euler Method

Sometimes the Cauchy-Euler method can get confusing and so this video will show you a much faster way to solving ODEs that use the Cauchy-Euler method.

Sturm-Liouville Problem (Part 1)

This video will find the particualr solution of a very common Sturm-Liouville Problem.

Sturm-Liouville Problem (Part 2)

Picking up where we left off, this video will finsih the last 2 parts of the problem.


Partial Differential Equation

Solving PDEs | Fourier Series


Solving Partial Differential Equations

Lecture | Time independent Solutions

In this lecture will learn a concept that will help us make solving PDEs easier.

General Solution of a PDE Using Separation of Variables

This series will have a different approach in teaching you by doing examples of the methods. In this example video, we will solve a simple PDE problem using the separation of variables method.

Wave Equation

Example | Method of Characteristic with a Direchlet Boundary Condition

In this example we will be solving a wave eqaution with a Direchlet boundary conditions using the method of characteristics

Fourier Series

Example | Constructing the Fourier Series of a Periodic Function

This video will show the process of evaluating any periodic function and creating the Fourier series of the periodic function

Example | Finding the Summationg of Periodic Functions

After finding the Fourier series, we can actually now use this to find the summation of infinite series. Additionally, this video will discuss Parseval's identity.