Khan/khan-exercises — pull request #32904 by karlanderson (2012-10-31 18:25:42+00:00)
Title: Add Simplifying square roots of negatives

Requested new exercise: Simplifying square roots of negative numbers.
Based on Simplifying radicals.
Added new option complex-radical for radical answer type.
Unit test is untested.
First exercise so looking for feedback before continuing.