Question

How can you tell from the graph of Molly's garden on the previous slide that it represents a proportional relationship?

Answer 1

The graph of a proportional relationship has the same unit rate, is a straight line, and starts at the origin.

Answer 2

A proportional relationship is a relation of the form:

Y = A*X

This means that if we have two variables, X and Y, for each unit that X grows, Y grows A times that.

And notice that the relation:

Y/A = X

is also a porportional relationship

This relationship can be expresed in a graph as a straight line that pases through the origin and has a constant unit of growht (in this case A) that is also called the "slope" of the line.