\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) ={\frac {y \left( x \right) \ln  \left( x \right) +\cosh \left( x \right) xa \left( y \left( x \right)  \right) ^{2}+\cosh \left( x \right) {x}^{3}b}{x\ln  \left( x \right) }}=0}
\]