Equation standards

I just realized that our preferred convention for writing LaTeX equations in this
book is to use the "\(" and "\)" notation, not "\(\(" and "\)\)" to signify the start
and end of a LaTeX equations. Please do two things: 1. - fix any existing
equations in chapter 1 and 2 and 2. Add a note to the CLAUDE.md file that this is
our preferred way of adding equations.

I can see both chapters use \(...\) for inline math and Chapter 2 also uses \(\(...\)\) for
display math. I'll convert these to \(...\) for inline and [...] for display math,
then update CLAUDE.md.