Identify proportional relationships

key notes:

Two variables have a proportional relationship if the ratio of one variable to the other is constant.

The graph of a proportional relationship between x and y is a straight line passing through the origin, (0, 0).

Learn with an example

Select the graphs that show a proportional relationship between x and y.

To determine whether a graph shows a proportional relationship between x and y, see if it is a straight line passing through the origin.

This graph is a straight line, but it does not pass through the origin.

So, this graph does not represent a proportional relationship between x and y.

So, this graph represents a proportional relationship between x and y.

Select the graphs that show a proportional relationship between x and y.

To determine whether a graph shows a proportional relationship between x and y, see if it is a straight line passing through the origin.

This graph is a straight line passing through the origin.

So, this graph represents a proportional relationship between x and y.

This graph is a straight line, but it does not pass through the origin.

So, this graph does not represent a proportional relationship between x and y.

Select the graphs that show a proportional relationship between x and y.

To determine whether a graph shows a proportional relationship between x and y, see if it is a straight line passing through the origin.

This graph is a straight line, but it does not pass through the origin.

So, this graph does not represent a proportional relationship between x and y.

This graph is a straight line passing through the origin.

So, this graph represents a proportional relationship between x and y.

let’s practice!