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7.2 Direct and Partial Variation (Rule of 4).notebook December 09, 2012 Unit 7: Linear Relations Lesson 2: Direct and Partial Variation (Rule of 4) Reminder: Quiz: Test: Partial Variation Example 1: A pizza company charges $12.00 for a large pizza, and $1.25 for each additional topping. Model this relation using: a) a table b) a graph c) an equation 1 7.2 Direct and Partial Variation (Rule of 4).notebook December 09, 2012 Direct Variation Example 2: The cost of M&M's at The Bulk Barn is $1.50 per 100 grams. Model this relation using: a) a table b) a graph c) an equation Summary Direct variation: A relationship between two variables in which one variable is a constant multiple of the other. an equation in the form of y = mx the graph of a direct variation is a straight line that passes through the origin. A partial variation has an equation of the form y = mx + b, where b represents the initial value and m represents the rate of change. The graph of a partial variation is a straight line that does not pass through the origin. Rule of 4 A relation can be represented in a variety of ways so that it can be looked at from different points of view. A mathematical relation can be described in four ways: using words using a diagram or a graph using numbers using an equation 2