\[ y(x) y''(x)+3 y(x) y'(x)-3 y'(x)^2-y(x)^2=0 \] ✓ Mathematica : cpu = 0.131868 (sec), leaf count = 25
\[\left \{\left \{y(x)\to \frac {c_2 e^x}{\sqrt {1-2 e^{x+c_1}}}\right \}\right \}\] ✓ Maple : cpu = 0.912 (sec), leaf count = 68
\[y \relax (x ) = -\frac {\sqrt {2}\, \sqrt {\left ({\mathrm e}^{x} c_{1}-c_{2}\right ) {\mathrm e}^{2 x}}}{2 \,{\mathrm e}^{x} c_{1}-2 c_{2}}\]