Answer: None of them are functions.
Step-by-step explanation:
By definition, a relation is a function if and only if each input value have an unique output value.
You need to remember that the input values are the x-values and the output values are the y-values.
In the first table you can observe that the input value 2 has two different output values:
[tex]x=2;y=11\\\\x=2;y=15[/tex]
Therefore, this relation is not a function.
Notice that in the second table the input value -4 has two different output values:
[tex]x=-4;y=-2\\\\x=-4;y=-5[/tex]
Therefore, this relation is not a function.
In the set [tex]\{(-5,-7), (-2,-7), (7,17), (-5,21)\}[/tex], observe that the input value -5 has two different output values:
[tex]x=-5;y=-7\\\\x=-5;y=21[/tex]
Therefore, this relation is not a function.
