Khan/khan-exercises — pull request #14889 by beneater (2012-02-29 00:34:06+00:00)
Title: Graphing parabolas!

Adds [Graphing parabolas 1](http://sandcastle.khanacademy.org/media/castles/beneater:graph-parabola/exercises/graphing_parabolas_1.html) and [Graphing parabolas 2](http://sandcastle.khanacademy.org/media/castles/beneater:graph-parabola/exercises/graphing_parabolas_2.html).

Both use @mathiash's formatter work for hint formatting! Need to fix a few minor nits in some formatting, for example simplifying a `1` or `-1` coefficient, but otherwise, graphing_parabolas_1 is pretty much ready.

graphing_parabolas_2 could use a little more tweaking of the hints for completing the square. I'd like opinions on whether the sub-hint format make sense for that step, or if I'm just being too eager to use a new toy. :)

@msuhendra thoughts?