\[ a y(x) y'(x)+f(x)+x y'(x)^2+x y(x) y''(x)=0 \] ✓ Mathematica : cpu = 0.0775087 (sec), leaf count = 108
\[\left \{\left \{y(x)\to -\sqrt {2} \sqrt {\int _1^x-K[2]^{-a} \left (c_1+\int _1^{K[2]}f(K[1]) K[1]^{a-1}dK[1]\right )dK[2]+c_2}\right \},\left \{y(x)\to \sqrt {2} \sqrt {\int _1^x-K[2]^{-a} \left (c_1+\int _1^{K[2]}f(K[1]) K[1]^{a-1}dK[1]\right )dK[2]+c_2}\right \}\right \}\] ✓ Maple : cpu = 0.49 (sec), leaf count = 106
\[ \left \{ y \left ( x \right ) ={\frac {1}{a-1}\sqrt {-2\, \left ( a-1 \right ) \left ( -{x}^{1-a}\int \!{\frac {{x}^{a}f \left ( x \right ) }{x}}\,{\rm d}x-{x}^{1-a}{\it \_C1}+\int \!f \left ( x \right ) \,{\rm d}x+{\it \_C2} \right ) }},y \left ( x \right ) =-{\frac {1}{a-1}\sqrt {-2\, \left ( a-1 \right ) \left ( -{x}^{1-a}\int \!{\frac {{x}^{a}f \left ( x \right ) }{x}}\,{\rm d}x-{x}^{1-a}{\it \_C1}+\int \!f \left ( x \right ) \,{\rm d}x+{\it \_C2} \right ) }} \right \} \]