Chapter 9 Rational Equations and

Funtions9.1 Inverse and Joint Variation

What do you remember about direct variation?

What do you think it means for something to vary inversely?

How do we represent that as an equation?

Direct variation means that when x increases, y increases!

y=kx

This means that when x increases, y decreases. OR when x decreases. y increases.

So...What does Joint Variation mean?...

It means the same as direct variation, but with two or more variables!

An example would be the formula for the area of a triangle with base “b” and height “h”

A=½ bh

Here Area varies jointly with the base and height. ½ would be our constant of variation!

Homework

9.1 # 21,25,29,31,33,39,41,43,45,47