\[ y(x) y''(x)+3 y(x) y'(x)-3 y'(x)^2-y(x)^2=0 \] ✓ Mathematica : cpu = 0.196927 (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 = 1.282 (sec), leaf count = 68
\[\left \{y \left (x \right ) = \frac {\sqrt {2}\, \sqrt {\left (c_{1} {\mathrm e}^{x}-c_{2}\right ) {\mathrm e}^{2 x}}}{2 c_{1} {\mathrm e}^{x}-2 c_{2}}, y \left (x \right ) = -\frac {\sqrt {2}\, \sqrt {\left (c_{1} {\mathrm e}^{x}-c_{2}\right ) {\mathrm e}^{2 x}}}{2 c_{1} {\mathrm e}^{x}-2 c_{2}}\right \}\]