coefficients and variation

coefficients and variation

In Problems 27 and 28 discuss how the methods of undetermined coefficients and variation of parameters can be combined to solve the given differential equation. Carry out your ideas.
27. 3y” – 6y’ + 30y = 15 sin x + ex tan 3x

28. y” – 2y’ + y = 4×2 – 3 + x–1ex