\documentclass[fleqn,12pt,a4paper]{report}
\usepackage{amsmath}
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\usepackage{xepersian}


\begin{document}
\begin{equation*}
\frac{dy}{dx} = c_{1} e^{x} -3c_{2} e^{-3x}\qquad , \qquad \frac{d^2 y}{dx^2}=c_{1} e^{x}+9 c_{2} e^{-3x} 
\Longrightarrow (c_{1} e^{x}-3 c_{2} e^{-3x})+(c_{1} e^{x}+9 c_{2} e^{-3x})-3(c_{1}e^{x}+c_{2} e^{-3x})\neq 0.

\end{equation*}
\end{document}