[Free Registration/Login may be required to access all resource tools.] Understand direct and inverse variation.

Purplemath offers an extensive explanation of direct and inverse variation, containing several examples and real-world applications.

Find a quick, concise explanation of Combined Variation. Hyperlinks are available to explain how variables can vary directly and inversely.

Twenty problems present a variety of practice with inverse and direct variation. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View Solution" button...

[Free Registration/Login may be required to access all resource tools.] Learn how to solve problems using scale and indirect measurement.

Provides an explanation and examples of variation.

This comprehensive study guide highlights the main terms and formulas needed to understand graphs of rational functions. Examples are included.

Site describes direct, inverse, and joint variation.

Based off of the hit television show NUMB3RS, this lesson exposes students to equations of variation (direct, inverse, and joint) in the real world, as well as having students work with such equations in the real world context. The...

This site from the University of Illinois offers an excellent simulation of the quadratic formula, where you can type in different values for a, b, and c, and then view the change in the answer for x.