Question

Which graph shows a set of ordered pairs that represents a function?

On a coordinate plane, solid circles appear at the following points: (negative 5, 4), (negative 3, 2), (negative 1, 3), (1, 1), (1, negative 2), (3, negative 3).
On a coordinate plane, solid circles appear at the following points: (negative 5, 2), (negative 4, negative 4), (negative 3, 4), (negative 2, 2), (2, negative 2), (4, 3).
On a coordinate plane, solid circles appear at the following points: (negative 4, 2), (negative 1, 4), (1, 0), (2, 3), (2, negative 3), (3, 1).
On a coordinate plane, solid circles appear at the following points: (negative 4, 2), (negative 3, negative 4), (negative 3, 4), (negative 2, 1), (2, negative 3), (3, negative 1).

Answer 1

The second graph: {(-5,2), (-4,-4), (-3,4), (-2,2), (2,-2), (4,3)}.

Reason: each x-value appears only once, so each input has a single output (passes the vertical line test). The other graphs have repeated x-values with different y-values (e.g. x=1 in graph 1, x=2 in graph 3, x=-3 in graph 4), so they are not functions.