\[ y'(x)=\frac {x \left (24 a^2 x^8 y(x)+a^3 x^{12}-32 a^2 x^6+192 a x^4 y(x)^2-256 a x^2 y(x)-256 a x^2+512 y(x)^3\right )}{64 a x^4+512 y(x)+512} \] ✓ Mathematica : cpu = 0.214201 (sec), leaf count = 81
\[\left \{\left \{y(x)\to \frac {1}{8} \left (-a x^4-8\right )+\frac {1}{512 \left (\frac {1}{512}-\frac {1}{\sqrt {-262144 x^2+c_1}}\right )}\right \},\left \{y(x)\to \frac {1}{8} \left (-a x^4-8\right )+\frac {1}{512 \left (\frac {1}{512}+\frac {1}{\sqrt {-262144 x^2+c_1}}\right )}\right \}\right \}\] ✓ Maple : cpu = 0.169 (sec), leaf count = 79
\[ \left \{ y \left ( x \right ) ={ \left ( -8+ \left ( -\sqrt {-{x}^{2}+{\it \_C1}}-1 \right ) a{x}^{4} \right ) \left ( 8+8\,\sqrt {-{x}^{2}+{\it \_C1}} \right ) ^{-1}},y \left ( x \right ) ={ \left ( 8+ \left ( -\sqrt {-{x}^{2}+{\it \_C1}}+1 \right ) a{x}^{4} \right ) \left ( -8+8\,\sqrt {-{x}^{2}+{\it \_C1}} \right ) ^{-1}} \right \} \]