Talk:Cost as a Function of Land Pressure and Investment Count/@comment-98.225.44.66-20150925041706/@comment-174.23.33.189-20150925122838

The issue is that you are not finding the area under the curve. You are finding the area of rectangles (with a width of one unit) under the curve, in other words this is a finite sum. So integrating a*x^2*b^x + c*b^x does produce the correct area under the curve, but does not give you the correct sum.