\[ \boxed { y \left ( x \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +x \left ( y \left ( x \right ) \right ) ^{2}-4\,x=0} \]
Mathematica: cpu = 0.015502 (sec), leaf count = 47 \[ \left \{\left \{y(x)\to -\sqrt {e^{2 c_1-x^2}+4}\right \},\left \{y(x)\to \sqrt {e^{2 c_1-x^2}+4}\right \}\right \} \]
Maple: cpu = 0.016 (sec), leaf count = 33 \[ \left \{ y \left ( x \right ) =\sqrt {{{\rm e}^{-{x}^{2}}}{\it \_C1}+4}, y \left ( x \right ) =-\sqrt {{{\rm e}^{-{x}^{2}}}{\it \_C1}+4} \right \} \]