In mathematics, to get a unique answer for n variables (that are unknown) you need at least n independent data points. Since you are looking at 2 data points, you need at least two independent equations to solve
that involve your values.
Your equation looks like an iterative equation but I think you should probably explain the relation between the constants and the value at each successive m.
Again (and this is for all mathematics), once you get n independent relations (which in this case n = 2) then you can get a unique solution.