\[ y'(x)=\frac {\frac {1}{2} x^4 \cos (2 y(x))+\frac {x^4}{2}-\frac {1}{2} x \sin (2 y(x))-\frac {1}{2} \sin (2 y(x))}{x (x+1)} \] ✓ Mathematica : cpu = 0.609762 (sec), leaf count = 43
\[\left \{\left \{y(x)\to \tan ^{-1}\left (\frac {3 x^4-4 x^3+6 x^2-12 x+12 \log (x+1)-25-12 c_1}{12 x}\right )\right \}\right \}\] ✓ Maple : cpu = 0.983 (sec), leaf count = 38
\[ \left \{ y \left ( x \right ) =\arctan \left ( {\frac {3\,{x}^{4}-4\,{x}^{3}+6\,{x}^{2}+12\,\ln \left ( 1+x \right ) -12\,{\it \_C1}-12\,x}{12\,x}} \right ) \right \} \]