Merge pull request #39 from Dick-Lane/master

Identify annual factor and distinguish it from effective rate per year.
Merge pull request #40 from Dick-Lane/master

Remove sentence about ln or log being used in answer.
Merge pull request #41 from Dick-Lane/master

Remove statements about "answer must be inequalities" since it is false
Fix bug 2789, tables need to be arrays in math mode
Fix bug (derivative evaluated at point outside of domain of function)
Fixed bug 2815, duplicate problem.
Duplicate problems
Improved wording
Duplicate problems
Duplicate problems
Duplicate problems
Fix bug 2779, duplicate problesm
Improve formating.
Fix blunder in computations for discrete compounding.
Also (1) use decimal value for rate,
(2) lengthen answer boxes to accomodate exact expressions