Decide whether the relation is a function. If it is a function, give the domain and the range.

Yes 2 are functions.

FOR FUNCTIONS

every x can have at most one y

BUT

a y can have more than 1 x

A function is a relation such that each member of the domain is paired with only one member of the range. 

In a function the first number can never be paired with more than one second number; however, in a function the second number can be paired with more than one first number (but doesn't have to be).

If each member of the domain is matched with one and only one member of the range and each member of the range is matched with one and only one member of the domain, it is a one-to-one function. If each member of the domain is matched with one and only one member of the range but the same member of the range is used more than once, it is a many-to-one function.

{ (1,7), (1,-7) }   domain: {1}     range: {7,-7}  Not a function becase 1 is paired with both 7 and -7.

{ (2,8), (2,-8) }   domain: {2}     range: {8,-8}  Not a function because 2 is paired with both 8 and -8.

{ (3,2), (5,4), (7,4) }    domain: {3,5,7}     range: {2,4}  It is a many-to-one function.  I don't know quite what to do with the 6; I suppose that it could be put in the rangle but I wouldn't do that.

{ (0,-6), (2,-4), (4,-2), (6,0) }    domain:  {0,2,4,6}     range:  {-6,-4,-2,0}  It is a one-to-one function.

so geno none of them are a function

Wait!  Two of these are functions!