\[ y'(x)=\frac {x \left (a^3 x^{12}+24 a^2 x^8 y(x)-32 a^2 x^6+192 a x^4 y(x)^2-256 a x^2 y(x)-256 a x^2+512 y(x)^3\right )}{64 a x^4+512 y(x)+512} \] ✓ Mathematica : cpu = 0.227092 (sec), leaf count = 81
DSolve[Derivative[1][y][x] == (x*(-256*a*x^2 - 32*a^2*x^6 + a^3*x^12 - 256*a*x^2*y[x] + 24*a^2*x^8*y[x] + 192*a*x^4*y[x]^2 + 512*y[x]^3))/(512 + 64*a*x^4 + 512*y[x]),y[x],x]
\[\left \{\left \{y(x)\to \frac {1}{8} \left (-a x^4-8\right )+\frac {1}{512 \left (\frac {1}{512}-\frac {1}{\sqrt {-262144 x^2+c_1}}\right )}\right \},\left \{y(x)\to \frac {1}{8} \left (-a x^4-8\right )+\frac {1}{512 \left (\frac {1}{512}+\frac {1}{\sqrt {-262144 x^2+c_1}}\right )}\right \}\right \}\] ✓ Maple : cpu = 0.054 (sec), leaf count = 79
dsolve(diff(y(x),x) = (-256*a*x^2*y(x)-32*a^2*x^6-256*a*x^2+512*y(x)^3+192*x^4*a*y(x)^2+24*y(x)*a^2*x^8+a^3*x^12)*x/(512*y(x)+64*a*x^4+512),y(x))
\[y \left (x \right ) = \frac {8+\left (-\sqrt {-x^{2}+c_{1}}+1\right ) a \,x^{4}}{-8+8 \sqrt {-x^{2}+c_{1}}}\]