First pass at Chapter 2

source/docinfo.ptx

@@ -5,9 +5,9 @@
 <!-- settings. -->
 <docinfo xmlns:xi="http://www.w3.org/2001/XInclude">
   <!-- A unique name for the book in a catalog; for example, see https://pretextbook.org/catalog.html and https://runestone.academy/ns/books/index. It contains a simple lowercase string with no dashes or other special characters. See https://pretextbook.org/doc/guide/html/sec-publishing-to-runestone-academy.html for more information. -->
-  <document-id>changeme</document-id>
+  <!-- <document-id>changeme</document-id> -->
   <!-- A brief description for the book in a catalog; see the links above. The @shelf is used only when publishing to Runestone; see https://runestone.academy/ns/books/index for a list of valid values. You must copy these @shelf names exactly, including capitalization. -->
-  <blurb shelf="AP Computer Science"> A simple string (no markup is allowed) to describe your book. </blurb>
+  <!-- <blurb shelf="AP Computer Science"> A simple string (no markup is allowed) to describe your book. </blurb> -->
 
 
   <!-- The next three lines are likely for mature projects only: -->
@@ -30,6 +30,7 @@
     \DeclareMathOperator{\Bin}{Bin}
     \DeclareMathOperator{\Geom}{Geom}
     \DeclareMathOperator{\Poiss}{Poiss}
+    \DeclareMathOperator{\Exp}{Exp}
   </macros>
 
   <!-- If you put any latex-image elements you can include preambles -->