Any of the different converters that have been mentioned here may work, but more than likely, you will find at least some problems with certain formulas. Because each of the different conversion programs use different processes or algorithms, it would be nearly impossible to write one document that would work for all of the different formats you want. For example, one converter might render a decent version for the mobi file, but the epub file turns out to be unreadable.
The best way I have found to address this is to convert all of your formulas to images. It's fairly simple to do by just taking a screenshot and opening it MS Paint or any other imaging software and then cropping out the portion of the image that you don't need. I have done this with great results for a number of books that I have formatted for others.
One word of caution, however. If you have large images due to long, complex formulas, then people using smaller reading devices (smart phones) may have a hard time enlarging the image enough to make it readable. You can test this by converting your file and then opening it on a smart phone to test it out before sending it off to be published. If the image is too large, you may want to break it up into sections from top to bottom. Don't ever section it from side to side because that will cause the images to appear out of order. If your formulas are too wide, you may have to rewrite them so that they can be displayed better from top to bottom.