\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) ={\frac { \left ( - \left ( y \left ( x \right ) \right ) ^{2}+4\,ax \right ) ^{2}}{y \left ( x \right ) }}=0} \]
Mathematica: cpu = 0.145018 (sec), leaf count = 105 \[ \left \{\left \{y(x)\to -\sqrt {4 a x-\sqrt {2} \sqrt {a} \tanh \left (\frac {2 \sqrt {2} a x-\sqrt {2} c_1}{\sqrt {a}}\right )}\right \},\left \{y(x)\to \sqrt {4 a x-\sqrt {2} \sqrt {a} \tanh \left (\frac {2 \sqrt {2} a x-\sqrt {2} c_1}{\sqrt {a}}\right )}\right \}\right \} \]
Maple: cpu = 0.187 (sec), leaf count = 286 \[ \left \{ y \left ( x \right ) ={\sqrt {4}\sqrt { \left ( {\it \_C1}\,{ {\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2 \,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) \left ( {\it \_C1}\, \left ( ax-{\frac {\sqrt {2}}{4}\sqrt {a}} \right ) {{\rm e}^{2 \,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \left ( ax+{\frac {\sqrt {2}}{4} \sqrt {a}} \right ) \right ) } \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) ^{-1}},y \left ( x \right ) =-{\sqrt {4}\sqrt { \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2} \sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2 \,ax \right ) }} \right ) \left ( {\it \_C1}\, \left ( ax-{\frac {\sqrt { 2}}{4}\sqrt {a}} \right ) {{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,a x \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) } } \left ( ax+{\frac {\sqrt {2}}{4}\sqrt {a}} \right ) \right ) } \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+ {{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) ^{- 1}} \right \} \]