\[ \boxed { 3\, \left ( {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) \right ) y \left ( x \right ) -5\, \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}=0} \]
Mathematica: cpu = 0.027504 (sec), leaf count = 20 \[ \left \{\left \{y(x)\to \frac {c_2}{\left (3 c_1+2 x\right ){}^{3/2}}\right \}\right \} \]
Maple: cpu = 1.576 (sec), leaf count = 17 \[ \left \{ -{\frac {3}{2} \left ( y \left ( x \right ) \right ) ^{-{\frac { 2}{3}}}}-{\it \_C1}\,x-{\it \_C2}=0 \right \} \]