\[ y'(x)=\frac {x \left (a y(x)^2+b x^2\right )^2}{a^{5/2} y(x)} \] ✓ Mathematica : cpu = 0.361914 (sec), leaf count = 115
\[\left \{\left \{y(x)\to -\sqrt {-\frac {b x^2}{a}+\frac {\sqrt {b} \tan \left (\frac {a^{3/2} b x^2+2 c_1}{a^{9/4} \sqrt {b}}\right )}{\sqrt [4]{a}}}\right \},\left \{y(x)\to \sqrt {-\frac {b x^2}{a}+\frac {\sqrt {b} \tan \left (\frac {a^{3/2} b x^2+2 c_1}{a^{9/4} \sqrt {b}}\right )}{\sqrt [4]{a}}}\right \}\right \}\] ✓ Maple : cpu = 0.322 (sec), leaf count = 460
\[y \relax (x ) = \frac {\sqrt {-a \left (c_{1} {\mathrm e}^{\frac {x^{2} \left (2 a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right )}{2 a^{\frac {3}{2}}}}+{\mathrm e}^{\frac {x^{2} \left (-2 a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right )}{2 a^{\frac {3}{2}}}}\right ) \left (\left (b \,x^{2}-a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}\right ) {\mathrm e}^{\frac {x^{2} \left (-2 a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right )}{2 a^{\frac {3}{2}}}}+c_{1} \left (a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right ) {\mathrm e}^{\frac {x^{2} \left (2 a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right )}{2 a^{\frac {3}{2}}}}\right )}}{a \left (c_{1} {\mathrm e}^{\frac {x^{2} \left (2 a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right )}{2 a^{\frac {3}{2}}}}+{\mathrm e}^{\frac {x^{2} \left (-2 a^{\frac {3}{2}} \sqrt {-\frac {b}{a^{\frac {3}{2}}}}+b \,x^{2}\right )}{2 a^{\frac {3}{2}}}}\right )}\]