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

If you mean one-to-one function then

for every input, you get one output
(x,y)
x=input
y=output

basically, x never repeats witha differnt y

look at them
1st one
not since we have (1,5) and (1,-3) the 1 repeats with 2 y's

2nd one
yes, no repeats

3rd one
not since (-2,-5) and (-2,9), -2 repeats with -5 and 9

4th one
not since we have (-3,1) (-3,2), (-3,-3) -3 repeats with 1,2,-3

answer is 2nd one or

{( 3,-1),(7,1),(-6,-1),(9,1),(2,-1)}

Afraction ? 2/3 - 1/3 = ?