The domain of a function is the range of values that x can take. In this case, we have a function of the form f(x)=mx+b, which is a linear function, in our equation m is 2 and b is 7, when you plot this line it looks like this:
As you can see, the line goes from minus infinity to infinity, then the domain of the function is:
[tex](-\infty,\infty)[/tex]
