Given:
The set of ordered pairs.
To find:
Which set of ordered pairs represents a function?
Solution:
A set of ordered pairs represents a function, if there exist unique output value for each input value.
In option A,
{(2, 9), (5, 9), (1, -6), (-5, 5)}
It is a function because all input has unique outputs.
In option B,
{(6, 6), (6, 8), (-8, -7), (-3, -8)}
For x=6, there exist two outputs y=6 and y=8. So, it is not a function.
In option C,
{(1, 8), (9, -3), (7, -4), (7, -6)}
For x=7, there exist two outputs y=-4 and y=-6. So, it is not a function.
In option D,
{(-5, -1), (-3, -7), (-5, 3), (-7, -4)}
For x=-5, there exist two outputs y=-1 and y=3. So, it is not a function.
Therefore, the correct option is A.
