You can use GeoGebra to compute marginal revenue, marginal cost and marginal profit. These are all very useful functions for helping you make financial projections. 
     GeoGebra Instruction 1
Algebra     View     under         View     in         Menu.         revenue               function                              as               R         =                     
cost               function                              as               C         =          
using one row for each function in Algebra View.         
R’ in a new row in Algebra View and press Enter. This is the marginal         revenue.         C’ in a new row in Algebra View and press Enter. This is the marginal         cost.         Expand(R’- C’) in a new row in Algebra View and press Enter. This is         the marginal profit.