Which set of ordered pairs represents a function?
{(9,4),(-1,2), (-3,3),(-1,-6)}
{(-7,4), (7,2), (1,2), (-4,-4)}
{(-8,4), (–8,1), (0, -1), (5, -6)}
{(–9,–8), (2,-4), (–9,8), (0, –4)}

Someone Please help ASAP

The 2nd ordered pair. {(-7,4), (7,2), (1,2), (-4,-4)}

Step-by-step explanation:

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this