Question

PLEASE HELP THANK YOU!!!

Answer 1

Answer:

Only C is a function

Step-by-step explanation:

To test whether a graph is a function you use the vertical line test.

If you can place a vertical line anywhere on the plane (in the domain of the "function" to be tested) and it intersects the curve at more than one point, the curve is not a function.

We see with A, wherever we put the vertical line it intersects twice.

With B, it intersects infinitely many times.

C is a function because wherever we put the vertical line, it only intersects once.

D is a function because it intersects twice providing we do not put it on the "tip" of the parabola.

The mathematical reasoning behind this is that a function must be well-defined, that is it must send every x-value to one specific y-value. There can be no confusion about where the function's input is going. If you look at graph B and I ask you what is f(3)? Is it 1? 2? 3? ... Who knows, it's not well-defined and so it's not a function. However if I ask you about C, whichever input value for x I give you, you can tell me to which y-value it gets mapped/sent to.