How to solve for the polynomial expression of a simple data matrix

Probably the data is not exactly fulfilling a polynomial or exponential equation, so would rather use a fitting function.

Look up expfit, polyfit or genfit in the help pages.

If you need more help, come back again, attach your worksheet and state which version of Prime you are using.

From the pic it doesn't seem to me that a polynomial or an exponential would be a good fit - but you are the one who should know what process the data stems from and what kind of function can be expected.

BTW, from the spreadsheet screenshot it looks like you had chosen the wrong plot type in Excel as the x values are shown equidistant which they actually aren't.

My guess is:

with

So use genfit.

Success!
Luc