\[ -(f(x)+3 y(x)) y'(x)+f(x) y(x)^2+y''(x)+y(x)^3=0 \] ✓ Mathematica : cpu = 0.0550825 (sec), leaf count = 75
\[\left \{\left \{y(x)\to \frac {-\int _1^x\exp \left (\int _1^{K[2]}f(K[1])dK[1]\right ) c_1dK[2]-c_2}{\int _1^x\int _1^{K[5]}\exp \left (\int _1^{K[4]}f(K[3])dK[3]\right ) c_1dK[4]dK[5]+c_2 x+1}\right \}\right \}\] ✓ Maple : cpu = 0.095 (sec), leaf count = 38
\[\left \{y \left (x \right ) = \frac {-c_{2}-\left (\int c_{1} {\mathrm e}^{\int f \left (x \right )d x}d x \right )}{c_{2} x +\int \int c_{1} {\mathrm e}^{\int f \left (x \right )d x}d x d x +1}\right \}\]