Question 607600
{(-3, 6), (-2, 7), (-1, 8), (0, 9)}
<pre>
Yes it's a function because the 1st coordinates, 
-3,-2,-1, and 0 are all different.

That's the requirement for a relation to be a function.
It doesn't matter whether the 2nd coordinates are all
different or not, but the 1st coordinates MUST all be
different, no two alike. 

Edwin</pre>