\[ y''(x)=-\frac {\left (a+3 x^2\right ) y'(x)}{x^3}-\frac {b y(x)}{x^6} \] ✓ Mathematica : cpu = 0.0094504 (sec), leaf count = 93
\[\left \{\left \{y(x)\to c_1 e^{-\frac {\sqrt {b} \left (-\frac {\sqrt {a^2-4 b}}{\sqrt {b}}-\frac {a}{\sqrt {b}}\right )}{4 x^2}}+c_2 e^{-\frac {\sqrt {b} \left (\frac {\sqrt {a^2-4 b}}{\sqrt {b}}-\frac {a}{\sqrt {b}}\right )}{4 x^2}}\right \}\right \}\] ✓ Maple : cpu = 0.099 (sec), leaf count = 45
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{-{\frac {1}{4\,{x}^{2}} \left ( -a+\sqrt {{a}^{2}-4\,b} \right ) }}}+{\it \_C2}\,{{\rm e}^{{\frac {1}{4\,{x}^{2}} \left ( a+\sqrt {{a}^{2}-4\,b} \right ) }}} \right \} \]