Answer
0 ≤ x ≤ 10
Explanation
The domain is the possible values that the variable [tex]x[/tex] can take.
The statement "the number of internet users f(x) after x years from the year 2000" is telling us that the x-axis represent the number of years, so the domain of the function is the number of years from 2000 to 2010.
Number of years = 2010 - 2000 = 10 years
So we know that [tex]x[/tex] is at most 10 years; therefore [tex]x\leq 10[/tex]
Since years can't be negative, we can also infer that x must be 0 or bigger than 0, so [tex]0\leq x[/tex]
Now we can combine both inequalities to find the reasonable domain of the function:
[tex]0\leq x\leq 10[/tex]
