domain and range

Question

What is the domain and the range  of f(x)=3x+4

Answer 1

The domain of a function can be restricted pretty much anyway you want.  However, in this case, they are looking for the set of x values that can be put into the function without causing a division by zero or a point discontinuity.  In the case of f(x) = 3x+4, there are no values of x that cause a problem so we can write the domain in interval notation as (-∞, ∞).  The range follows from the domain and is also (-∞, ∞).