Which of the following relations shows a function?

Question

A.  {(-5, 6), (4, -3), (2, -1), (4, 2)}

B. {(3, -1), (3, -5), (3, 4), (3, 6)}

C. {(-2, 3), (0, 3), (-2, -1), (-1, 2)}

D. {(-5, 6), (-4, -3), (2, -1), (4, 2)}

Answer 1

D. {(-5, 6), (-4, -3), (2, -1), (4, 2)} because the graph of these points will pass the vertical line test.

 

All the others contain duplicated x values, with differing y values, so those points (with duplicated x's) would graph one above the other, and thus would not pass the V.L.T.