\begin{equation*}
9y''+6y'+y=0
\end{equation*}
\begin{equation*}
9r^2+6r+1=0
\end{equation*}
\begin{equation*}
(3r+1)^2=0
\end{equation*}
\begin{equation*}
r_1=r_2=-\frac{1}{3}\\
\end{equation*}
\begin{equation*}
y=C_1e^{-\frac{1}{3}t}+C_2te^{\frac{1}{3}t}
\end{equation*}
