\[ y'(x)=\frac {\left (4 a x-y(x)^2\right )^2}{y(x)} \] ✓ Mathematica : cpu = 0.134522 (sec), leaf count = 95
\[\left \{\left \{y(x)\to -\sqrt {4 a x-\sqrt {2} \sqrt {a} \tanh \left (\frac {\sqrt {2} \left (2 a x-c_1\right )}{\sqrt {a}}\right )}\right \},\left \{y(x)\to \sqrt {4 a x-\sqrt {2} \sqrt {a} \tanh \left (\frac {\sqrt {2} \left (2 a x-c_1\right )}{\sqrt {a}}\right )}\right \}\right \}\]
✓ Maple : cpu = 0.283 (sec), leaf count = 286
\[ \left \{ y \left ( x \right ) ={\sqrt {4}\sqrt { \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) \left ( {\it \_C1}\, \left ( ax-{\frac {\sqrt {2}}{4}\sqrt {a}} \right ) {{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \left ( ax+{\frac {\sqrt {2}}{4}\sqrt {a}} \right ) \right ) } \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) ^{-1}},y \left ( x \right ) =-{\sqrt {4}\sqrt { \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) \left ( {\it \_C1}\, \left ( ax-{\frac {\sqrt {2}}{4}\sqrt {a}} \right ) {{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \left ( ax+{\frac {\sqrt {2}}{4}\sqrt {a}} \right ) \right ) } \left ( {\it \_C1}\,{{\rm e}^{2\,x \left ( \sqrt {2}\sqrt {a}-2\,ax \right ) }}+{{\rm e}^{-2\,x \left ( \sqrt {2}\sqrt {a}+2\,ax \right ) }} \right ) ^{-1}} \right \} \]