Find the general solution of the system
\begin{aligned}&x^{\prime}=4 x+y, \\&y^{\prime}=-8 x+8 y .\quad\quad\quad\quad\quad (12)\end{aligned}Find the general solution of the system
\begin{aligned}&x^{\prime}=4 x+y, \\&y^{\prime}=-8 x+8 y .\quad\quad\quad\quad\quad (12)\end{aligned}