Another one from G.F.Simmons' "Differential Equations": Chapter 2 Miscellaneous Exercises no. 20:
This can be put in the format:
Substituting , from which
which leads to:
This leads to the messy:
Flogging through the calculus and after tidying up:
which is miles away from the given answer:
(although that looks promising)
If I try solving it by doing:
and dividing T&B by and substuting it's even worse.
I must be doing something fundamentally wrong in the first few lines but for the life of me I can't work out what.