gistfile1.txt

\documentclass[11pt,a4paper]{article}
 

\title{\LaTeX}
\author{dupa}
\date{}
 
\begin{document}

\begin{equation}
    ln(f) = ln(\frac{d^2 - c^2}{4d}) = ln(d^2 - c^2) - ln(4d) = ln(d-c) +ln(d+c) - ln(4) - ln(d)
\end{equation}
\begin{equation}
\frac{\Delta f}{f} = \frac{\Delta (d-c)}{d-c} + \frac{\Delta (d+c)}{d+c)} - \frac{\Delta d}{d}
\end{equation}
\begin{equation}
   \Delta f = \frac{\Delta(d-c)(d-c)(d+c)}{(d-c)*4d} + \frac{\Delta(d+c)(d-c)(d+c)}{(d+c)*4d} - \frac{\Delta d(d-c)(d+c)}{4d^2} = \frac{\Delta d*d^2 + \Delta d*d*c - \Delta c*d^2 - \Delta c*c*d}{4d^2} + \frac{\Delta d *d^2 - \Delta d*c*d +\Delta c * d^2 - \Delta c*c*d}{4*d^2} - \frac{\Delta d*d^2 - \Delta d*c^2}{4*d^2} = \frac{\Delat d*d^2 - \Delta c*d^2 - 2 * \Delta c *d*c}{4*d^2}
\end{equation}
 
\end{document}