Question

Pls explain how this works?

Answer 1

Domain is the set of all inputs (x-axis)
Range is the set of all outputs (y-axis)

For something to be a function it has to pass the “vertical line test”. If you can put vertical lines throughout the entire graph and the lines are only intersected once (per line) then it’s a function.

For this particular one, it is not a function because it fails the vertical line test.
How?
If I were to put a vertical line through -2 on the y-axis then both points (2,-2) and (6,-2) would be on said line. Therefore it’s NOT a function.

Answer 2

Because the domain refers to the set of possible input values, the domain of a graph consists of all the input values shown on the x-axis. The range is the set of possible output values, which are shown on the y-axis.