# Understanding proportionality in mathematics

Created by Tiago Hands. Graphs can be reproduced @http://www.graphfree.com.

y is directly proportional to x.

1. Using the proportionality symbol, we can say that y∝x.

2. The formula which is related to the graph above can be written like so y=kx. ‘k’ is the constant of proportionality.

y is directly proportional to x squared.

1. Using the proportionality symbol, we can say that y∝x².

2. The formula which is related to the graph above can be written like so y=kx². ‘k’ is the constant of proportionality.

y is directly proportional to x cubed.

1. Using the proportionality symbol, we can say that y∝x³.

2. The formula which is related to the graph above can be written like so y=kx³. ‘k’ is the constant of proportionality.

y is inversely proportional to x squared.

1. Using the proportionality symbol, we can say that y∝1/x².

2. The formula which is related to the graph above can be written like so y=k/x². ‘k’ is the constant of proportionality.

y is inversely proportional to x.

1. Using the proportionality symbol, we can say that y∝1/x.

2. The formula which is related to the graph above can be written like so y=k/x. ‘k’ is the constant of proportionality.

y is directly proportional to the square root of x.

1. Using the proportionality symbol, we can say that y∝√x.

2. The formula which is related to the graph above can be written like so y=k√x. ‘k’ is the constant of proportionality.