Equations

An equation expresses a relationship between (usually) two or more variables. For an equation to be a function there is only one output for each input.

For example:

In Economics, supply and demand are each represented by an equation.

Each equation has 2 variables: price () in dollars and quantity demanded ().

Demand Curve: 

Supply Curve: 

A value for  can be substituted into the equation.

When the demand curve tells us the price

Review the use of  order of operations as well as  positive and negative numbers to ensure you evaluate the equation correctly.

Function notation:

For example:

Let denote the bank balance after days.

This is the function where the value of the bank balance is dependent on , the number of days.

    The value of the bank balance is after days.

Further information

• Press the Printer Friendly button at the bottom left-hand corner to download a printable handout
• RMIT University has online  videos to review the use of  equations.
• Khan academy online videos show more details about  interpreting function notation.