# How do you find the domain and range of f(x) = 3x + 1 ?

Because there are no restrictions on the input to the function (the value of $x$), the domain is the set of all Real Numbers or $\left\{\mathbb{R}\right\}$
Because this is a simple linear transformation, the output is also the set of all Real Numbers or $\left\{\mathbb{R}\right\}$