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.  They each have  (quantity demanded) as a variable.

Each equation has 2 varianblea: 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      

(remember order of operations)