auxiliary equation

In Problems 55– 58 use a computer either as an aid in solving the auxiliary equation or as a means of directly obtaining the general solution of the given differential equation. If you use a CAS to obtain the general solution, simplify the output and, if necessary, write the solution in terms of real functions.
55. y'” – 6y” + 2y’ + y = 0
56. 6.11y'” + 8.59y” + 7.93y’ + 0.778y = 0
57. 3.15y(4) – 5.34y” + 6.33y’ – 2.03y = 0

58. y(4) + 2y” – y’ + 2y = 0