Answer: Choice B
{(0,0), (1,2), (2,4), (3,4)}
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Explanation:
A function is only possible if each x input leads to exactly one y output. For choice A, we have x = 1 lead to y = 3 and y = 5 at the same time, which is what the points (1,3) and (1,5) are saying. Therefore, choice A is not a function.
Choice C is also ruled out because x = 2 repeats itself as well. In this case, (2,3) and (2,4) means that the input x = 2 leads to the two outputs y = 3 and y = 4.
Choice D can be eliminated also for two reasons: x = 0 shows up twice, so does x = 2.
Only choice B has each x value listed one time only. So that means each input leads to exactly one output.
If you graph choice A, C or D, you'll find they fail the vertical line test. The vertical line test is where you test if you can draw a vertical line through more than one point on the graph. If you can draw a vertical line through more than one point on the graph, then the relation fails to be a function.
