\[ y'(x)=-\frac {e^x \left (-8 y(x)^{9/2}+36 e^x y(x)^3-8 y(x)^3+24 e^x y(x)^{3/2}-54 e^{2 x} y(x)^{3/2}-18 e^{2 x}+27 e^{3 x}-8\right )}{8 \sqrt {y(x)}} \] ✗ Mathematica : cpu = 300.585 (sec), leaf count = 0 , timed out
$Aborted
✓ Maple : cpu = 1.159 (sec), leaf count = 49
\[ \left \{ {{\rm e}^{x}}-{\frac {2}{3}\ln \left ( \left ( y \left ( x \right ) \right ) ^{{\frac {3}{2}}}-{\frac {3\,{{\rm e}^{x}}}{2}}+1 \right ) }-4\, \left ( -6\, \left ( y \left ( x \right ) \right ) ^{3/2}+9\,{{\rm e}^{x}} \right ) ^{-1}+{\frac {2}{3}\ln \left ( \left ( y \left ( x \right ) \right ) ^{{\frac {3}{2}}}-{\frac {3\,{{\rm e}^{x}}}{2}} \right ) }-{\it \_C1}=0 \right \} \]