Which set of ordered pairs in the from of (x, y) does not represent a function of x?

{ (1,1.5), (2,1.5), (3,1.5) (4,1.5) } (my guess)

{ (0,1.5), (3,2.5), (1,3.3), (1, 4.5) }

{ (1,1.5), (-1,1.5), (2,2.5), (-2,2.5) }

{ (1,1.5), (-1,-1.5), (2,2.5), (-2,-2.5) }

The second set/line of ordered pairs is not a function.

Specifically the pairs: (1, 3.3) and (1, 4.5).

This is because they are two different pairs with 1 as their x value but 2 different numbers as their y value.

And this is a problem because:

For every x value of a true function, there is only one y value.

Think of it like this:

f (x) = x is a simple fiction with with which whatever you input, you get out (F (x) is a fancy way of saying that whatever number is in place of x in f (x) is what you replace all the X's in the equation with).

An example:

f (3) = 3

So, you couldn't take that same function and get f (3) = 5

That is what it means when I say that a function can only have one y value (y value is just another way of saying the number the function equals) for every x value (x value is another way of saying the number that you plug into the function).