\[ y''(x)=\frac {y(x)}{f(x)}-\frac {x y'(x)}{f(x)} \] ✓ Mathematica : cpu = 0.0513118 (sec), leaf count = 46
\[\left \{\left \{y(x)\to c_2 x \int _1^x\frac {\exp \left (-\int _1^{K[2]}\frac {K[1]}{f(K[1])}dK[1]\right )}{K[2]^2}dK[2]+c_1 x\right \}\right \}\] ✓ Maple : cpu = 0.071 (sec), leaf count = 30
\[ \left \{ y \left ( x \right ) =x \left ( \int \!{{\rm e}^{\int \!{\frac {1}{x} \left ( -2-{\frac {{x}^{2}}{f \left ( x \right ) }} \right ) }\,{\rm d}x}}\,{\rm d}x{\it \_C1}+{\it \_C2} \right ) \right \} \]