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\begin{document}
\[ \]
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\medskip

\textbf{Main}:
\begin{eqnarray}
،\frac{\partial^{\alpha}u}{\partial t^{\alpha}}+(\beta+\varepsilon\ u^{p}+\epsilon\ u^{2p} ) u_{x}+\rho \ u^{2r}\ u_{xx}+\nonumber  \\
،\nu \ u^{3s}\ u_{xxx}+\vartheta\ u^{4k}\ u_{xxxx}=
\eta u(\tau-u^{m})(u^{n}-\omega),\\
،t>0,\ 0<\alpha<1,\ \beta=\varepsilon=\epsilon=\rho=\nu=\vartheta=\eta=\omega=const,\ p,r,s,k,m,n\geq 0 \nonumber 
\end{eqnarray}

\bigskip
\textbf{eqnarray with \&}:
\begin{eqnarray}
&،\frac{\partial^{\alpha}u}{\partial t^{\alpha}}+(\beta+\varepsilon\ u^{p}+\epsilon\ u^{2p} ) u_{x}+\rho \ u^{2r}\ u_{xx}+\nonumber  \\
& \qquad ،\nu \ u^{3s}\ u_{xxx}+\vartheta\ u^{4k}\ u_{xxxx}= \eta u(\tau-u^{m})(u^{n}-\omega),\\
& ،t>0,\ 0<\alpha<1,\ \beta=\varepsilon=\epsilon=\rho=\nu=\vartheta=\eta=\omega=const,\ p,r,s,k,m,n\geq 0 \nonumber 
\end{eqnarray}

\bigskip
\textbf{align with \&}:
\begin{align}
&\frac{\partial^{\alpha}u}{\partial t^{\alpha}}+(\beta+\varepsilon\ u^{p}+\epsilon\ u^{2p} ) u_{x}+\rho \ u^{2r}\ u_{xx}+\nonumber  \\
& \qquad \nu \ u^{3s}\ u_{xxx}+\vartheta\ u^{4k}\ u_{xxxx}=
\eta u(\tau-u^{m})(u^{n}-\omega),\\
&t>0,\ 0<\alpha<1,\ \beta=\varepsilon=\epsilon=\rho=\nu=\vartheta=\eta=\omega=const,\ p,r,s,k,m,n\geq 0 \nonumber 
\end{align}

\bigskip
\textbf{split}:
\begin{equation}
    \begin{split}
	  &\frac{\partial^{\alpha}u}{\partial t^{\alpha}}+(\beta+\varepsilon\ u^{p}+\epsilon\ u^{2p} ) u_{x}+\rho \ u^{2r}\ u_{xx}+  \\
	  & \qquad \nu \ u^{3s}\ u_{xxx}+\vartheta\ u^{4k}\ u_{xxxx}=   \eta u(\tau-u^{m})(u^{n}-\omega),\\
	  &t>0,\ 0<\alpha<1,\ \beta=\varepsilon=\epsilon=\rho=\nu=\vartheta=\eta=\omega=const,\ p,r,s,k,m,n\geq 0 
    \end{split}
\end{equation}

\end{document}