Global Apple iPod sales between $2006$ and $2014$ can be modeled as

$A(x)=-1\mathrm{.}427x^2+24\mathrm{.}766x-54\mathrm{.}44$ million iPods, where $x$ is the number of

years since $2000.$

The input notation is

and the input units are

The input description is

$.$

The output notation is

and the output units are

The output description is

The input interval can be written asDetermine the type of representation that a function has when presented in each of the following ways.

equation

table

graph

description of how the input and output variables are related to each other