Answer
(a) algebraic
(b) Input is the number of years since 2004, measured in the unit years.
Output is the number of cell phones recycled, measured in the unit million phones.
(c) The relation is a function because each input value has a unique output value.
(d)
$x years$
$\downarrow$
$\huge{\Box}$
$\ \ \ \ \downarrow$
$\ \ \ \ \mathcal{R}(x)\ million\ phones$
Work Step by Step
(a) An equation is an algebraic representation.
(b) This equation shows that the number of cell phones that are recycled has increased each year since 2004. The input to the equation is the number of years since 2004, so the unit of measurement is "years". The result of the equation is the number of cell phones recycled in the given year. The output is the number of cell phones recycled. The unit of measurement is "million phones".
(c) Since the relation shows that the number of phones recycled each year increases over time, so the relation is a function because each input value has a unique output value.
(d) The input output diagram should show the number of years entering the function and the output is the number of cell phones recycled.
