Hello Kevin,
I took a long while to prepare for the Exam2 because I wanted to master the math.
To my disappointment, the PRM book for Exam2 is very lacking both in material and exercises. You cannot learn the math by just reading; you need to do a lot of exercises. So I returned to and studied from my college-time books; both calculus and stats. I also bought some books on the subjects of matrices and linear equations, and numerical analysis.
So my recommendation is to dust off those college books and keep it beside you when studying.
Thamir