I'm not sure which sub-board this goes in, so I'm sorry if I chose wrong.

How can you find the sum of all points of an exponential within a certain range? That is:

f(x) = a * x ^ y

I figure the result would be same as the area of the region underneath the curve, above the x-axis, and between the two points (start and end), as highlighted pink in the graph (not included due to errors uploading), but I'm not finding a formula for that either.