The standart form for a first order linear differential equation is given by

\(y'+p(x)y=q(x)\)

we have \(\displaystyle{y}'={x}^{{{3}}}{y}+{\sin{{\left({x}\right)}}}\)

\(\displaystyle{y}'-{x}^{{{3}}}{y}={\sin{{\left({x}\right)}}}\)

where \(\displaystyle{p}{\left({x}\right)}=-{x}^{{{3}}}\) and \(q(x)=\sin(x)\)