Introduction to systems of equations

9 videos
5 skills
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". This tutorial shows you how to solve systems of equations graphically.

Trolls, tolls, and systems of equations

VIDEO 6:51 minutes
A troll forces us to use algebra to figure out the make-up of his currency. We end up setting up a system of equations.

Solving the troll riddle visually

VIDEO 5:41 minutes
Solving the system of equations visually. Now we can save the prince/princess.

How to solve a system of linear equations graphically (example)

VIDEO 2:22 minutes
Sal graphs the following system of equations and solves it by looking for the intersection point: y=7/5x-5 and y=3/5x-1.

Solve systems of equations graphically

PRACTICE PROBLEMS
Graph a system of equations in slope-intercept or standard form, and find their solution using the graphs.

King's cupcakes: Solving systems by elimination

VIDEO 9:00 minutes
Sal uses simple elimination to figure out how many cupcakes are eaten by children and adults.

How many bags of potato chips do people eat?

VIDEO 9:21 minutes
Sal solves another system of equations using elimination.

How to solve a system of linear equations with elimination (basic example)

VIDEO 4:18 minutes
Sal solves the following system of equations by eliminating x: x-4y=-18 and -x+3y=11.

Solve systems of linear equations with elimination (basic)

PRACTICE PROBLEMS
Solve systems of equation with one-step elimination (e.g., x-values or y-values cancel each other out).

Systems with elimination practice

VIDEO 5:31 minutes
Example of solving systems of equations with elimination

Solve systems of linear equations with elimination (advanced)

PRACTICE PROBLEMS
Solve systems of equation with multi-step elimination (e.g., a manipulation is need in order for x-values or y-values to cancel each other out).

Talking bird solves systems of equations with substitution

VIDEO 5:21 minutes
Sal solves a systems of equations with substitution.

How to solve a system of linear equations with substitution (example)

VIDEO 4:21 minutes
Sal solves the following system of linear equations using substitution: -3x-4y=-2 and y=2x-5.

Solve systems of linear equations with substitution

PRACTICE PROBLEMS
Solve systems of equations where one of the equations is solved for one of the variables.

Solve any system of two linear equations

PRACTICE PROBLEMS
Solve systems of equations with any number of solutions using any solution method.