Time for action – swapping out preamble and chapter contents

We begin to write an extensive document about equations and equation systems. The result should be in the style of a thesis or a book. We can use the last example in Chapter 8, TypingMath Formulas, where we dealt with theorems concerning equations.

1. Create a new document. Inside this, load all the packages and specify the options, like we did in our preambles before. Use all the beneficial packages that we already learned about:

   \usepackage[english]{babel}
   \usepackage[utf8]{inputenc}
   \usepackage[T1]{fontenc}
   \usepackage{lmodern}
   \usepackage{microtype}
   \usepackage{natbib}
   \usepackage{tocbibind}
   \usepackage{amsmath}
   \usepackage{amsthm}
   \newtheorem{thm}{Theorem}[chapter]
   \newtheorem{lem}[thm]{Lemma}
   \theoremstyle{definition}
   \newtheorem{dfn}[thm]{Definition}

2. Save this document under the name preamble.tex.

3. Start another new document and copy the contents of the chapter Equations in the theorem example of Chapter 8 into it:

   \chapter{Equations...