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Khan Academy on a Stick

Algebra I

A system for solving the King's problems

Whether in the real world or a cliche fantasy one, systems of equations are key to solving super-important issues like "the make-up of change in a troll's pocket" or "how can order the right amount of potato chips for a King's party." Join us as we cover (and practice with examples and exercises) all of the major ways of solving a system: graphically, elimination, and substitution. This tutorial will also help you think about when system might have no solution or an infinite number of solutions. Very, very exciting stuff!

Super fast systems of equations

Have no time for trolls, kings and parrots and just want to get to the essence of system. This might be a good tutorial for you. As you can see, this stuff is so important that we're covering it in several tutorials!

Solving systems graphically

This tutorial focuses on solving systems graphically. This is covered in several other tutorials, but this one gives you more examples than you can shake a chicken at. Pause the videos and try to do them before Sal does.

Thinking about solutions to systems

You know how to solve systems of equations (for the most part). This tutorial will take things a bit deeper by exploring cases when you might have no solutions or an infinite number of them.

Solving systems with substitution

This tutorial is focused on solving systems through substitution. This is covered in several other tutorials, but this one focuses on substitution with more examples than you can shake a dog at. As always, pause the video and try to solve before Sal does.

Solving systems with elimination (addition-elimination)

You can solve a system of equations with either substitution or elimination. This tutorial focuses with a ton of examples on elimination. It is covered in other tutorials, but we give you far more examples here. You'll learn best if you pause the videos and try to do the problem before Sal does.

Systems of equations word problems

This tutorial doesn't involve talking parrots and greedy trolls, but it takes many of the ideas you might have learned in that tutorial and applies them to word problems. These include rate problems, mixture problems, and others. If you can pause and solve the example videos before Sal does, we'd say that you have a pretty good grasp of systems. Enjoy!

Systems of inequalities

You feel comfortable with systems of equations, but you begin to realize that the world is not always fair. Not everything is equal! In this short tutorial, we will explore systems of inequalities. We'll graph them. We'll think about whether a point satisfies them. We'll even give you as much practice as you need. All for 3 easy installments of... just kidding, it's free (although the knowledge obtained in priceless). A good deal if we say so ourselves!

Systems with three variables

Two equations with two unknowns not challenging enough for you? How about three equations with three unknowns? Visualizing lines in 2-D too easy? Well, now you're going to visualize intersecting planes in 3-D, baby. (Okay, we admit that it is weird for a website to call you "baby.") Tired of linear systems? Well, we might just bring a little nonlinearity into your life, honey. (You might want to brush up on your solving quadratics before tackling the non-linear systems.) As always, try to pause the videos and do them before Sal does!

Modeling constraints

In this tutorial, we'll use what we know about equations, inequalities and systems to answer some very practical real-world problems (and a few fake, impractical ones as well just for fun).