A lot of these "formulas" become way easier to understand once you've derived them yourself (a few times), just as a heads up. Memorizing mathematics, if you care about taking it seriously for the long term, should be done at a minimum.
For sure, but a cheat sheet can still be useful. For example, the I find matrix cookbook very useful when I don't feel like rederiving derivatives of nontrivial linear algebra expressions.
https://github.com/melling/MathAndScienceNotes/tree/master/s...
I did a little write-up on my blog:
https://h4labs.wordpress.com/2017/12/30/learning-probability...