I know some people want to spell Microsoft with a $ instead of the s, and certainly some of their products are not cheap. But today my daughter (who is a 14 year old 8th grader) pointed me to Microsoft Mathematics 4.0, a fantastic free program that does math, plots etc etc.
To think that for little more than 350 USD you can get a small PC that will run this beauty and more – back in its day the Texas Instruments TI-59 was 300 USD!
The Microsoft Mathematics even features a Word plugin, that will actually let you do part of your Math (and other) homework directly within Word.
On the left hand side of the Mathematics screen is a calculator like device, that is really just a shortcut to the various formulas that are supported.
It is the worksheet window where the real lifting is done. Here you can see how the system explains how a simple equation is solved:
It sounds like a cliché, but there are just too many features to easily explain, so you really have to have a go yourself and download it!
If you happen to run Mac or Linux there is of course the (also free) option of GeoGebra