Answer:
18] not a function; (1, 5), (1, -1)
19] is a function
Step-by-step explanation:
The graph of a function will pass the "vertical line test." That is, a vertical line will not intersect the graph at more than one point.
18] There are an infinite number of points where a vertical line will cross the graph twice. Two that are recognizable are the ones at the vertical extremes: (1, 5) and (1, -1). This relation is not a function.
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19] None of the points on the graph are vertically aligned, so the relation is a function.
