Is the following relation a function?
{(3.-5). (1.,-4). (-2, 2)}
o yes
o no

Yes, because you have different inputs, each associated with its output: your pair of values are suggesting a function f such that

So, you're never associating an input with two different outputs, so the relation is a function.

If, for example, you added the point (3, 55), you would introduce ambiguity, because you'd have

but also

which is not acceptable for a function.