Understand that a relationship between two variables, x and y, is proportional if it can be expressed in the form yx = k or y = kx. Distinguish proportional relationships from other relationships, including inversely proportional relationships (xy = k or y = kx).
For example: The radius and circumference of a circle are proportional, whereas the length x and the width y of a rectangle with area 12 are inversely proportional, since xy = 12 or equivalently, y = 12x.
Benchmark: 7.2.1.2 Graph of a Proportional Relationship
Understand that the graph of a proportional relationship is a line through the origin whose slope is the unit rate (constant of proportionality). Know how to use graphing technology to examine what happens to a line when the unit rate is changed.
Understand the concept of proportionality in real-world and mathematical situations, and distinguish between proportional and other relationship
On a seperate piece of paper, tell whether y is directly proportional to x. If
so, find the constant of proportionality. Then write a direct proportion
equation.
