\[ y(x) f'(x)+2 f(x) y'(x)+y^{(3)}(x)=0 \] ✗ Mathematica : cpu = 0.0730264 (sec), leaf count = 0 , could not solve
DSolve[y[x]*Derivative[1][f][x] + 2*f[x]*Derivative[1][y][x] + Derivative[3][y][x] == 0, y[x], x]
✗ Maple : cpu = 0. (sec), leaf count = 0 , result contains DESol
\[ \left \{ y \left ( x \right ) = \left ( {\it DESol} \left ( \left \{ {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}{\it \_Y} \left ( x \right ) +{\frac {f \left ( x \right ) {\it \_Y} \left ( x \right ) }{2}} \right \} , \left \{ {\it \_Y} \left ( x \right ) \right \} \right ) \right ) ^{2} \right \} \]