Answer:
A is not a function
B is a function
C is a function
D is a function
E is not a function
F is a function
G is not a function
Explanation:
A is not a function because there are multiple outputs for the same input. In this case, the outputs 7 and -7 both have the same input of 1, and the outputs 8 and-8 both have the same input of 2. In order for a relationship to be a function, there must only exist one unique output for every input, no more, no less.
B is a function because each input is assigned one unique output
C is a function because each input is assigned one unique output (and also happens to be linear)
D is a function because no x-coordinate contains more than one y-coordinate, via the vertical line test
E is not a function because the x-coordinate of 3 has y-coordinates of both 3 and -1, which would fail the horizontal line test.
F is a function because no x-coordinate contains more than one y-coordinate, via the vertical line test
G is not a function because it fails the horizontal line test since there are multiple x-coordinates with multiple outputs assigned to them.