\documentclass[12pt]{article}
\usepackage{amsmath,amsfonts, amssymb}
\usepackage{graphicx}
\usepackage{trimclip}
\usepackage{xepersian}
\settextfont[ExternalLocation,Scale=4]{XB Zar}
\setmathdigitfont{XB Zar}
\newcommand*{\Kashida}[4]{%
	\leavevmode
	#1\char"200D %
	\llap{\clipbox{-1ex 0pt {\width} 0pt}{#2}}%
	\resizebox{#3}{\height}{\clipbox{0pt}{#2}}%
	\rlap{\clipbox{{\width} 0pt -1ex 0pt}{#2}}%
	\char"200D #4%
}

\begin{document}
		\vspace*{\fill}
		\begin{center}
			\medskip 
			\Kashida{فص}{ـ}{100pt}{ل}			  	
			\vspace{2cm}
					\Kashida{س}{ـ}{50pt}{وم}
			

انتگرال گیری عددی
		\end{center}
		\vspace*{\fill}
		\newpage
		\mbox{}
		\begin{flushright}
			
\tiny
			

مقدمه: فرض کنید
 $ \delta = \lbrack a=x_{0} \rbrack 
  $

		\end{flushright}

\end{document}