5.1.2 Linear ode with non-constant coefficients

Euler type \(x^{3}y^{\prime \prime \prime }+x^{2}y^{\prime \prime }+xy^{\prime }+y=f\left ( x\right ) \)
Missing \(y\) as in \(ay^{\prime \prime \prime }+by^{\prime \prime }+cy^{\prime }=f\left ( x\right ) \)
Solved using reduction of order
Solved by series method