These are the section covered so far:

3.1: higher order ODE's and BVP's

3.2: reduction of order

3.3: constant coefficients

3.4: undetermined coefficients

3.5: variation of parameters

3.5: Cauchy-Euler equations

I know a couple of the questions are arbitrary but any professional answer will help and please include explination. Choose from any of the sections above for part a and b

(a) Which topic from this section is most useful? (not easiest). Explain why (ls). (b) Which topic from this section is least useful? (not hardest). Explain why (1s). (C) Write an appropriate initial value problem using: (:3 + 42)2y'\" + $33,143; = ex. Then, explain how the IVP theorem tells you Where a solution is guaranteed (28)