Question

Determine whether the relation is also a function.

{(-6, -4), (-2, -9), (4, 5), (4, 6)}

yes or no

Answer 1

Mh.
Since you've got two possible values of y for the same x (4,5) and (4,6)
I would say that there is non function y=f(x) that touches all the points.

i.e. no