\[ a y'(x)+b y(x)+y''(x)=0 \] ✓ Mathematica : cpu = 0.00587939 (sec), leaf count = 58
\[\left \{\left \{y(x)\to c_1 e^{\frac {1}{2} x \left (-\sqrt {a^2-4 b}-a\right )}+c_2 e^{\frac {1}{2} x \left (\sqrt {a^2-4 b}-a\right )}\right \}\right \}\]
✓ Maple : cpu = 0.012 (sec), leaf count = 45
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{ \left ( -{\frac {a}{2}}+{\frac {1}{2}\sqrt {{a}^{2}-4\,b}} \right ) x}}+{\it \_C2}\,{{\rm e}^{ \left ( -{\frac {a}{2}}-{\frac {1}{2}\sqrt {{a}^{2}-4\,b}} \right ) x}} \right \} \]