\documentclass[12pt,a4paper]{article}
\usepackage[left=1.00cm, right=1.00cm, top=1.00cm, bottom=1.00cm]{geometry}
\usepackage{fontspec}
\usepackage{amsmath,amsfonts,amssymb}
\usepackage{graphicx}
\usepackage{xcolor}

\usepackage{tikz}
\usetikzlibrary{shapes,decorations.text}

\usepackage{hyperref}
\hypersetup{
    colorlinks=true,
    linkcolor=blue
}

\usepackage{polyglossia}
\setmainlanguage[numerals=maghrib]{arabic}
\newfontfamily\arabicfont[Script=Arabic, Scale=1.3]{Amiri}

\newcommand{\mylink}{\href{https://mosaid.xyz/cc}{www.mosaid.xyz}}

\newcommand{\stamp}[2]{
\begin{tikzpicture}[remember picture, overlay]
\coordinate (A) at (#1,#2);
\draw[red!50] (A) circle (1.9cm);
% Draw the inner circle
\draw[red!50] (A) circle (1.4cm);
% Draw the curved line
\draw[red!50, decorate, decoration={text along path,
	text={|\fontspec{DejaVu Sans}\color{red!75}\bfseries|★MOSAID RADOUAN★},
	text align={align=center}, raise=-3pt}] (A) ++ (180:1.6cm) arc (180:0:1.6cm);
\draw[decorate, decoration={text along path,
	text={|\fontspec{DejaVu Sans}\color{red!75}\bfseries|∞★~mosaid.xyz~★∞ },
	text align={align=center}, raise=-6.5pt}] (A) ++ (180:1.53cm) arc (-180:0:1.53cm);
\node[red!75,font=\fontsize{48}{48}\fontspec{DejaVu Sans}\bfseries\selectfont] at (A) {✷};
\end{tikzpicture}
} %end stamp


\newcommand{\schema}{%
\scalebox{0.75}{%
\begin{tikzpicture}[
    scale=0.2,
    node distance=2cm,
    every node/.style={draw, rectangle, minimum height=1cm, minimum width=4cm, align=center},
    arrow/.style={-latex, thick},
    highlight/.style={fill=yellow!20},
    important/.style={draw, shape=circle, minimum height=0.5cm, minimum width=0.5cm, fill=red!20, align=center}
]

% Nœuds pour chaque étape
\node (equations) [highlight] {$ax^2 + bx + c = 0$};
\node (determinant) [below of=equations] {$\Delta = b^2-4ac$};
\node (casepositive) [important, below left of= determinant, xshift=-1cm, yshift=-0.5cm] {$\Delta > 0$};
\node (casezero) [important, right of= casepositive, xshift=1cm] {$\Delta = 0$};
\node (casenegative) [important, right of= casezero, xshift=1cm] {$\Delta < 0$};

% Branche pour Delta non nul
\node (solution) [highlight, below left of=casenegative, xshift=-10cm, yshift=-1cm] {
	\textarabic{حلي المعادلة هما :}\\
	$x_1=\dfrac{-b-\sqrt{\Delta}}{2a} ~;~ x_2=\dfrac{-b+\sqrt{\Delta}}{2a}$
};

% Branche pour Delta nul
\node (casesingle) [highlight, right of= solution, xshift=5cm ] {$\dfrac{-b}{2a}$
	\textarabic{الحل الوحيد للمعادلة هو :}
};

\node (casenosolution) [highlight, right of= casesingle, xshift=4cm] {$S=\varnothing$
	\textarabic{المعادلة ليس لها حل :}
};

% Flèches entre les étapes
\draw[arrow] (equations) -- (determinant);
\draw[arrow] (determinant) -- (casepositive);
\draw[arrow] (determinant) -- (casezero);
\draw[arrow] (determinant) -- (casenegative);
\draw[arrow] (casepositive) -- (solution);
\draw[arrow] (casenegative) -- (casenosolution);
\draw[arrow] (casezero) -- (casesingle);

\end{tikzpicture}
}%end scalebox
}% end schema

\begin{document}
\thispagestyle{empty}
\centering
\schema\stamp{2}{4}\\
\vspace*{2cm}
\schema\stamp{2}{4}\\
\vspace*{2cm}
\schema\stamp{2}{4}\\
\end{document}