Complete question is:
The function f(x) = 600 - 100x models the value, f(x), of a video game system x years after purchase. Which choice represents the most appropriate domain of the function?
Answer and explanation:
The domain of a function is the values you can plug into the function, the possible values for x.
While x could take any value, there are a range of apropiate values that it can take.
For example, since x represents years after purchase, x can not be a negative number, because that would represent negative years, thus x must be greater or equal to 0.
Domain:
[tex]\lbrack0,\infty)[/tex]