Grosse formule...

\documentclass[12pt,landscape]{article}
\usepackage{tikz}
\usepackage{euler}
\begin{document}
\thispagestyle{empty}

\centerline{
\begin{tikzpicture}[every node/.style = {scale=4}]
  \node at (0,0) {$(a+b)^2 = a^2 + 2 ab + b^2$} ;
  \node at (0,-4) {$\exp(a + b) = \exp(a) \times \exp(b)$} ;
  \node at (0,-8) {$\ln(a \times b) = \ln(a) + \ln(b)$} ;
\end{tikzpicture}
}

\end{document}

\documentclass{article}

\usepackage[a4paper,landscape,margin=1cm]{geometry}
\usepackage{anyfontsize}
\usepackage{amsmath}

\pagestyle{empty}
\begin{document}
{\fontsize{80}{100}
\[a^2+b^2=(a+b\mathrm{i})(a-b\mathrm{i})\]}
{\fontsize{65}{70}
  \[a^n-b^n=(a-b)\sum_{k=0}^{n-1}a^kb^{n-k-1}\]}
{\fontsize{75}{80}
  \[(a+b)^n=\sum_{k=0}^{n}\binom{n}{k}a^kb^{n-k}\]}
\end{document}