# Graphing a curve for cumulative repayments

I have a formula in an excel spreadsheet that calculates compounding interest over a period of time in 20 different cells, reducing the amount in each increment using the following formula:

pv*(1+int)^y=amt


This code generates a linear decrease across the period directly from point a to point b.

What I am trying to do is have a field that can determine a curve based on how quickly payments are made up front?

i.e. Currently displays like this

And now I want a field to enter a number which determines that curve:

i.e. Entering 100 might do this (i.e. repay 100% more each increment ):

NOTE: I want the number (100) to be adjustable to change the view of the graph

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