Answer:
Domain: {-4, -2, 1, 2, 4}
Range: {-4, -2, -1, 1, 4}
The relation is a function. 
Step-by-step explanation:
A <u>relation</u> is any set of ordered pairs, which can be thought of as (input, output). 
A function is a <em>relation</em> in which no two ordered pairs have the same first component and different second components. 
Remember that a function can only take on <u>one output for each input</u>. We cannot plug in a value and get out two values. 
The Vertical Line Test allows us to know whether or not a graph is actually a function.  If a vertical line intersects the graph in all places <u><em>at exactly one point</em></u>, then the relation is a function. 
I did the Vertical Line Test on your given graph. As you can see from the attached screenshot, each vertical line crosses the graph only once. Therefore, the given relation is a function.
The <u><em>domain</em></u> of the given relation is the set of x-values, while the <em><u>range</u></em> is the set of y-values. You'll have to list the ordered pairs in order to determine the domain and range of the given relation.
Relation:  {(-4, -1), (-2, 1), (1, -2), (2, 4), (4, -4)}.
Domain: {-4, -2, 1, 2, 4}
Range: {-4, -2, -1, 1, 4}
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