\[ y^{(3)}(x)+3 y'(x)-4 y(x)=0 \] ✓ Mathematica : cpu = 0.00800787 (sec), leaf count = 54
\[\left \{\left \{y(x)\to c_3 e^x+c_1 e^{-x/2} \sin \left (\frac {\sqrt {15} x}{2}\right )+c_2 e^{-x/2} \cos \left (\frac {\sqrt {15} x}{2}\right )\right \}\right \}\] ✓ Maple : cpu = 0.013 (sec), leaf count = 35
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{x}}+{\it \_C2}\,{{\rm e}^{-{\frac {x}{2}}}}\sin \left ( {\frac {\sqrt {15}x}{2}} \right ) +{\it \_C3}\,{{\rm e}^{-{\frac {x}{2}}}}\cos \left ( {\frac {\sqrt {15}x}{2}} \right ) \right \} \]