\[ \left (x^4+y(x)^2\right ) y'(x)-4 x^3 y(x)=0 \] ✓ Mathematica : cpu = 0.118486 (sec), leaf count = 53
\[\left \{\left \{y(x)\to \frac {1}{2} \left (c_1-\sqrt {4 x^4+c_1{}^2}\right )\right \},\left \{y(x)\to \frac {1}{2} \left (\sqrt {4 x^4+c_1{}^2}+c_1\right )\right \}\right \}\] ✓ Maple : cpu = 0.312 (sec), leaf count = 41
\[\left \{y \left (x \right ) = \frac {c_{1}}{2}-\frac {\sqrt {4 x^{4}+c_{1}^{2}}}{2}, y \left (x \right ) = \frac {c_{1}}{2}+\frac {\sqrt {4 x^{4}+c_{1}^{2}}}{2}\right \}\]