\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) ={\frac {y \left ( x \right ) \ln \left ( x \right ) +\cosh \left ( x \right ) xa \left ( y \left ( x \right ) \right ) ^{2}+\cosh \left ( x \right ) {x}^{3}b}{x\ln \left ( x \right ) }}=0} \]
Mathematica: cpu = 0 (sec), leaf count = 0 \[ \text {Hanged} \]
Maple: cpu = 0.047 (sec), leaf count = 39 \[ \left \{ y \left ( x \right ) ={\frac {x}{a}\tan \left ( \int \!{\frac {x \cosh \left ( x \right ) }{\ln \left ( x \right ) }}\,{\rm d}x\sqrt {ab}+ {\it \_C1}\,\sqrt {ab} \right ) \sqrt {ab}} \right \} \]