\[ \left \{x'(t)+2 x(t)+y'(t)+y(t)=t+e^{2 t},x'(t)-x(t)+y'(t)+3 y(t)=e^t-1\right \} \] ✓ Mathematica : cpu = 0.108001 (sec), leaf count = 118
\[\left \{\left \{x(t)\to \frac {1}{5} \left (t-e^t+e^{2 t}+1\right )+\frac {5}{72} \left (\frac {12 \left (5712 t+833 e^t+2352 e^{2 t}-5508\right )}{20825}+c_1 e^{-7 t/5}\right ),y(t)\to \frac {1}{5} \left (-t+e^t-e^{2 t}-1\right )+\frac {5}{48} \left (\frac {12 \left (5712 t+833 e^t+2352 e^{2 t}-5508\right )}{20825}+c_1 e^{-7 t/5}\right )\right \}\right \}\] ✓ Maple : cpu = 0.082 (sec), leaf count = 51
\[\left \{\left \{x \left (t \right ) = c_{1} {\mathrm e}^{-\frac {7 t}{5}}+\frac {3 t}{7}-\frac {{\mathrm e}^{t}}{6}+\frac {5 \,{\mathrm e}^{2 t}}{17}-\frac {1}{49}, y \left (t \right ) = \frac {3 c_{1} {\mathrm e}^{-\frac {7 t}{5}}}{2}+\frac {t}{7}+\frac {{\mathrm e}^{t}}{4}-\frac {{\mathrm e}^{2 t}}{17}-\frac {26}{49}\right \}\right \}\]