\[
\boxed{
{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) + \left( y \left( x \right) -3/2\,{\frac {{\frac {\rm d}{{\rm d}x}}f \left( x \right) }{f \left( x \right) }} \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) - \left( y \left( x \right)  \right) ^{3}-1/2\,{\frac { \left( {\frac {\rm d}{{\rm d}x}}f \left( x \right)  \right)  \left( y \left( x \right)  \right) ^{2}}{f \left( x \right) }}+1/2\,{\frac {y \left( x \right) }{f \left( x \right) } \left( f \left( x \right) +{\frac { \left( {\frac {\rm d}{{\rm d}x}}f \left( x \right)  \right) ^{2}}{ \left( f \left( x \right)  \right) ^{2}}}-{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}f \left( x \right)  \right) }=0}
\]