\[
\boxed{
3\, \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) \sin \left( x \right) \sin \left( y \left( x \right)  \right) +5\, \left( \cos \left( x \right)  \right) ^{4}y \left( x \right) =0}
\]