An athlete is training to run a marathon. she plans to run 2 miles the first week. she increases the distance by 8% each week. whixh function models how far she will run in the nth week

This is the theory of exponential growth. Given that the an athlete is training to run marathon and she plans to run 2 miles in the first week and increase the distance by 8%. The function modeling how far she will run the nth week will be given by
nth=ae^(bx)
nth=2e^(0.08x)
where x is the nth time. 

Where are the functions?