The equations these:

$$\begin{array}{rl}\frac{\mathrm{d}x}{\mathrm{d}t}& =-3x-5y\\ \frac{\mathrm{d}y}{\mathrm{d}t}& =5x+3y\end{array}$$

What method for solving this system?

$$\begin{array}{rl}\frac{\mathrm{d}x}{\mathrm{d}t}& =-3x-5y\\ \frac{\mathrm{d}y}{\mathrm{d}t}& =5x+3y\end{array}$$

What method for solving this system?