So far you have mostly worked with equations. There are special types of equations, called functions, that have exactly one output for every possible input into the equation. An example of this in the real world is the amount of money you are charged at a store: the input is the item you are purchasing, and the output is the money you are charged. Individual items have one price, so this is an example of a function. Can you think of any other examples of functions? Why might this type of equation be useful?

Question

mathmale · Answer

Think:  one unique output (y-value) for any given input (x-value) within the function domain.  
Even if you're completely unsure, share your thoughts about what else in our lives is governed by a function.  How about the price of postage for a given weight?