Added exercise 5.9
Merge pull request #81 from Fugacity59/master

Changed step function in example 2.9
Merge pull request #82 from kyliefenner/master

Exercise 5.9
Merge pull request #3 from alchemyst/master

Updating repo
Sage version of Example 5.8
Merge pull request #83 from bsaaiman/master

Sage version of Example 5.8