\[ 3 y^{(4)}(x) y''(x)-5 y^{(3)}(x)^2=0 \] ✓ Mathematica : cpu = 0.0343404 (sec), leaf count = 28
\[\left \{\left \{y(x)\to c_2 \left (-\sqrt {3 c_1+2 x}\right )+c_4 x+c_3\right \}\right \}\]
✓ Maple : cpu = 0.687 (sec), leaf count = 30
\[ \left \{ y \left ( x \right ) =3\, \left ( {\it \_C2}+x \right ) \sqrt {6}{{\it \_C1}}^{2}\sqrt {-{\frac {{\it \_C1}}{{\it \_C2}+x}}}+{\it \_C3}\,x+{\it \_C4} \right \} \]