
\begin{enumerate}
\item $y' +4y = 0 \iff y' = -4y \iff \boxed{ y(x)=C\e^{-4x}\quad,\quad C\in\R}$.
\item $y'-2y=0 \iff y' = 2y \iff \boxed{ y(x)=C\e^{2x}\quad,\quad C\in\R}$.
\item $y'+\dfrac{1}{3}y=0 \iff y' = -\dfrac{1}{3}y \iff \boxed{ y(x)=C\e^{-\frac{1}{3}x}\quad,\quad C\in\R}$.
\end{enumerate}
