Asked by Britnee

Which set of ordered pairs is not a function?A. (4, –2), (–2, 2), (2, –2), (4, 2)
B. (–4, 2), (–2, 2), (2, 2), (4, 2)
C. (–4, 2), (–2, –2), (2, 2), (4, 2)
D. (–4, –2), (–2, –2), (2, 2), (4, 2)
Answered by MathMate
Look for ordered pairs (x,y) with identical x-values. If the corresponding y-values are different, the ordered pairs do not form a function. This is the equivalent of the vertical line test (i.e. no vertical line cuts two points).

However, in case where both x and y values are identical, that means the points are just duplicates, and does not violate the vertical line test. Look for others, if any.

In (A), what can you say about the pair of ordered pairs indicated in bold?
A. <b>(4, –2)</b>, (–2, 2), (2, –2), <b>(4, 2)</b>
Answered by Damon
In A there are two values of y , -2 and + 2, for the same value of x, 4

That is a no no
Answered by Steve
if a value of x maps to two different y's, it is not a function.

So, look for a line with a repeated 1st element.
Answered by Britnee
I don't understand
Answered by Steve
If y=f(x) maps a value of x to a value of y, then look at the first line. It says

f(4) = -2
f(4) = 2

it cannot be both. So, (A) is not a function.
Answered by Ms. Sue
Three math teachers explained this to you. I suggest that you study your text or hire a math tutor who can help you in person.