\[ y^{(3)}(x)+3 y'(x)-4 y(x)=0 \] ✓ Mathematica : cpu = 0.0065108 (sec), leaf count = 54
\[\left \{\left \{y(x)\to c_3 e^x+c_2 e^{-x/2} \cos \left (\frac {\sqrt {15} x}{2}\right )+c_1 e^{-x/2} \sin \left (\frac {\sqrt {15} x}{2}\right )\right \}\right \}\] ✓ Maple : cpu = 0.01 (sec), leaf count = 35
\[\left \{y \left (x \right ) = c_{2} {\mathrm e}^{-\frac {x}{2}} \sin \left (\frac {\sqrt {15}\, x}{2}\right )+c_{3} \cos \left (\frac {\sqrt {15}\, x}{2}\right ) {\mathrm e}^{-\frac {x}{2}}+c_{1} {\mathrm e}^{x}\right \}\]