Question

find the domain of the following function below. f(x)=3x-5/2

Answer 1

The domain of the function would be all real numbers. (-infinity, +infinity).
The domain of a linear function is asking what are the x values and because it is a line, it goes in both directions forever. 

Answer 2

The domain is:
$- \infty,\infty$
This is because there are no Real numbers that cause the function to be undefined.