1. Direct Variation Direct Variation: y y
A constant proportional relationship between two variables
Two ways to solve direct variation:
y = k*x (save for 11th or 12th grade pre-calc)
Direct proportion:
x = x
y y
We will use direct proportions this year

2. Direct Variation First Example:
A car can travel on 420 miles on a full 20 gallon tank of gas.
If there are only 7 gallons of gas in the tank, how many miles can the car travel?
Miles = Miles
Gallons Gallons
420 = x
Solve the Equation, x = 147

3. Direct Variation Example 2:
The scale on the map is 5cm = 3.5 miles. How far apart are two towns that are 8cm apart on the map?