#### Answer

domain: $\left\{3\right\}$
range: $\left\{-\infty, +\infty\right\}$
Refer to the graph below.

#### Work Step by Step

RECALL:
The line $x=a$, where $a$ is a real number::
(a) is vertical. All points on this line have an x-coordinate of $a$;
(b) has the set of real numbers as its range; and
(c) has a domain of $\left\{a\right\}$
Thus, the graph of the equation $x=3$ is a vertical line.
All points on the line have an x-coordinate of $3$.
The domain is $\left\{3\right\}$.
The range is $\left\{-\infty, +\infty\right\}$.
The line contains the points $(3, 0)$ and $(3, 3)$.
Plot the points above and connect them using a line.
(Refer to the graph in the answer part above.)