\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) ={\frac {y \left ( x \right ) +{x}^{3}a{{\rm e}^{x}}+a{x}^{4}+a{x}^{3}-x \left ( y \left ( x \right ) \right ) ^{2}{{\rm e}^{x}}-{x}^{2} \left ( y \left ( x \right ) \right ) ^{2}-x \left ( y \left ( x \right ) \right ) ^{2}}{x}}=0} \]
Mathematica: cpu = 0.057007 (sec), leaf count = 48 \[ \left \{\left \{y(x)\to \sqrt {a} x \tanh \left (\frac {1}{6} \sqrt {a} \left (6 c_1+2 x^3+3 x^2+6 e^x x-6 e^x\right )\right )\right \}\right \} \]
Maple: cpu = 0.031 (sec), leaf count = 46 \[ \left \{ y \left ( x \right ) =\tanh \left ( {\frac {{x}^{3}}{3}\sqrt {a} }+x{{\rm e}^{x}}\sqrt {a}+{\frac {{x}^{2}}{2}\sqrt {a}}-{{\rm e}^{x}} \sqrt {a}+{\it \_C1}\,\sqrt {a} \right ) x\sqrt {a} \right \} \]