
\def\alpha{8} 

\newcommand\myheading[1]{%
\par\bigskip
{\Large\bfseries#1}\par\smallskip}


\newcommand\derivative[5]{%
    \tkzDefPointByFct[draw](#1) \tkzGetPoint{start}
  \tkzDefPointByFct[draw](#2) \tkzGetPoint{end}
  \draw[thin,|-|,yshift=-3pt] (start) -- node[black,fill=white,#5] {#3}(start-|end);  
  \draw[thin,|-|,xshift=3pt] (start-|end) -- node[black,fill=white,right] {#4}(end); 
  %\draw[thin] (start) --(end); 
}