\[ \boxed { {x}^{2}{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +{x}^{2}{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) + \left ( ax+b \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 0.030004 (sec), leaf count = 122 \[ \left \{\left \{y(x)\to c_1 e^{\frac {1}{2} \left (\left (\sqrt {1-4 b}+1\right ) \log (x)-2 x\right )} U\left (\frac {1}{2} \left (-2 a+\sqrt {1-4 b}+1\right ),\sqrt {1-4 b}+1,x\right )+c_2 e^{\frac {1}{2} \left (\left (\sqrt {1-4 b}+1\right ) \log (x)-2 x\right )} L_{\frac {1}{2} \left (2 a-\sqrt {1-4 b}-1\right )}^{\sqrt {1-4 b}}(x)\right \}\right \} \]
Maple: cpu = 0.062 (sec), leaf count = 41 \[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{-{\frac {x}{2}}}}{ {\sl M}_{a,\,{\frac {1}{2}\sqrt {1-4\,b}}}\left (x\right )}+{\it \_C2}\, {{\rm e}^{-{\frac {x}{2}}}}{{\sl W}_{a,\,{\frac {1}{2}\sqrt {1-4\,b}} }\left (x\right )} \right \} \]