Time for action – discussing quadratic equations and roots

Our first small math text shall deal with the solutions of quadratic equations. We need to typeset formulas with constants, variables, superscripts for the square, and subscripts for the solutions. The solution itself needs a root symbol. Finally, we will use cross-references to formulas.

1. Start a new document. For now, we don't need any package:

   \documentclass{article}
   \begin{document}
   \section*{Quadratic equations}

2. State the quadratic equation with its conditions. Use an equation environment for it. Surround small pieces of math within text by \( … \):

   The quadratic equation
   \begin{equation}
     \label{quad}
   ax^2 + bx + c = 0,
   \end{equation}
   where \( a, b \) and \( c \) are constants and \( a \neq 0 \),
   has two solutions for the variable \( x \):

3. Use another equation for the solutions. The command for the square root is \sqrt. The command for a fraction is \frac:

   \begin{equation}
     \label{root}
     x_{1,2} = \frac{-b \pm \sqrt{b^2-4ac}}{2a...