ship wrote...
In the table below, the inputs are the values in columns "A" and "B
and the desired output is column "C".

A B C

-3 -3 0
-3 +3 -6
+3 -3 0
+3 +3 +6
0 0 0

What on earth is the formula in Microsoft Excel that creates "C"?
....

Another possibility, C1: =(B10)*2*A1

If this is would be a differentiable function at every (x,y) point,
then none of the formulas offered so far would be correct. There's an
infinite number of polynomials in x and y that could pass through
these 5 (x,y) points.