Khan Academy: Variables and Expressions: Expressions With Two Variables

Can an equation have an infinite number of solutions? Allow your class to discover the relationship between the input and output variables in a two-variable equation. Class members explore the concept through tables and graphs and...

The example of two travelers meeting somewhere along the road has been a stereotypical joke about algebra as long as algebra has existed. Here in this detailed presentation, this old trope gets a careful and approachable treatment....

Introduce learners to independent and dependent variables with an informative video.The two variables are defined via inputs and outputs. It makes clear that the independent variable is the one that the person has control over,...

Video continuing to show how to parameterize a torus using two parameters by writing the position vector valued functions. [16:32]

This video demonstrates how to evaluate an expression with two variables using substitution.

Video evaluating an exponential expression using the order of operations.

This video demonstrates how to write a two variable inequality given the graph of the inequality on a coordinate plane. Practice problems available. [3:20]

Video expands on medical example from previous video and explains the difference between a one-tailed and two-tailed hypothesis test, when they would be used, and gives an example of calculating a one-tailed test. [6:34]

Explore improper integral with two infinite bounds.

A demonstration of finding the limit of a function using two horizontal asymptotes.