\[ y(x) f'(x)+2 f(x) y'(x)+y^{(3)}(x)=0 \] ✗ Mathematica : cpu = 0.0483734 (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
\[\left \{y \left (x \right ) = \mathit {DESol}\left (\left \{\frac {\textit {\_Y} \left (x \right ) f \left (x \right )}{2}+\frac {d^{2}}{d x^{2}}\textit {\_Y} \left (x \right )\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )^{2}\right \}\]