Answer
Not a function.
Domain: [3, $\infty$)
Range: $(-\infty,\ \infty)$
Work Step by Step
This graph is not a function because it fails the vertical line test -- a vertical line can pass the graph in two points, indicating that there can be two different $y$ values for one $x$ value (not a function).
We can see that the range is all real numbers and the domain is all values greater than or equal to $3$:
Domain: [3, $\infty$)
Range: $(-\infty,\ \infty)$
