LaTeX Forum

\begin{tabular}{|l|l|l|}
\hline  &  &Unbestimmte Formen    \\ 
\hline  Summen, Differenzen & $ a\pm \infty = \pm \infty $ & $\infty - \infty $   \\
\hline Produkte &  $(\pm \infty)(\pm \infty) = \infty $ & 0($ \pm \infty $)  \\
				&  $(\infty)(-\infty) = \infty $ &  \\ 
				&  $a>0: a(\pm \infty) = \pm \infty $ &  \\ 
				&  $a<0: a(\pm \infty) = \mp \infty $ &  \\ 				
\hline Quotienten & $ \frac{a}{\pm \infty} = 0 $&$   \frac{0}{0} ; \frac{\pm\infty }{\pm\infty} $\\ 
$a \neq 0	$	&	$\mid\frac{\pm \infty}{0}\mid = \infty $& \\
				&	$\mid\frac{a}{0}\mid = \infty $&\\
\hline 	Potenzen&	$ a>1: a^{\infty} = \infty$&$1^{\infty}, 0^{0}, \infty^{\infty} $\\
				&	$ a\in (0,1): a^{\infty}=0   a^{-\infty}=\infty $&\\
				&	$ a>0: \infty^{a}=\infty $ &\\
				&	$ a<0: \infty^{a}=0 $&\\
				&	$ 0^{\infty}=0 $&\\
				&	$ \infty ^{-\infty}=0 $&\\
				&	$ \infty ^{\infty}=\infty 	$&\\
\hline 		
\end{tabular} 

\listfiles
\documentclass[ngerman]{scrartcl}

\usepackage{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

\begin{document}

\begin{tabular}{|l|rcl|l|}
\hline  &  &  &  & Unbestimmte Formen    \\
\hline  Summen, Differenzen & $ a\pm \infty$ &=& $\pm \infty $ & $\infty - \infty $   \\
\hline Produkte &  $(\pm \infty)(\pm \infty)$ &=& $\infty $ & 0($ \pm \infty $)  \\
            &  $(\infty)(-\infty)$ &=& $\infty $ &  \\
            &  $a>0: a(\pm \infty)$ &=& $\pm \infty $ &  \\
 
\hline      
\end{tabular} 

\end{document}

\begin{tabular}{|l|r@{}c@{}l|l|}