\[ \left \{x'(t)=-5 x(t)-2 y(t),y'(t)=x(t)-7 y(t)\right \} \] ✓ Mathematica : cpu = 0.0136633 (sec), leaf count = 52
\[\left \{\left \{x(t)\to e^{-6 t} \left (\left (c_1-2 c_2\right ) \sin (t)+c_1 \cos (t)\right ),y(t)\to e^{-6 t} \left (\left (c_1-c_2\right ) \sin (t)+c_2 \cos (t)\right )\right \}\right \}\]
✓ Maple : cpu = 0.038 (sec), leaf count = 44
\[ \left \{ \left \{ x \left ( t \right ) ={{\rm e}^{-6\,t}} \left ( \cos \left ( t \right ) {\it \_C2}+\sin \left ( t \right ) {\it \_C1} \right ) ,y \left ( t \right ) =-{\frac { \left ( \left ( {\it \_C1}-{\it \_C2} \right ) \cos \left ( t \right ) -\sin \left ( t \right ) \left ( {\it \_C1}+{\it \_C2} \right ) \right ) {{\rm e}^{-6\,t}}}{2}} \right \} \right \} \]