The function f (x) is the total amount spent at a store, when purchasing x items that are $5 each and the items are not taxable.

What is the practical domain for the function f (x) ?

all positive integers

all real numbers

all whole numbers

all positive integers that are multiples of 5

First lets write out this function to get a better grasp of what x values, (domain) would apply.

f (x) = 5x

The key word here is practical, a negative amount of items does not make sense so we can cross, whole numbers and real numbers off the list.

Positive integers that are multiples of 5 does not make sense, why would a shopper be restricted to buying items in pairs of five?

The most logical and only choice left is all positive integers.

F (x) = 5x

normal domain: all real numbers

practical domain: all positive integers

becasue we can substituent with any positive integer in the place of x