Answer:
[tex]\text{Domain: }\lbrace-3,3,7\rbrace[/tex]Step-by-step explanation:
The domain of a set of ordered pairs is the set of the first number in every pair (which are the x-coordinate), then, for the points of the graph above:
A(-3,7)
B(3,7)
C(7,3)
D(-3,-7)
Therefore, its domain would be:
[tex]\text{Domain: }\lbrace-3,3,7\rbrace[/tex]