(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I'm looking to solve a DE for a problem I have but I haven't done so in a while and must be forgetting something. I've checked the answer in Mathematica and what I'm getting is wrong.

u''(r)+1/r u'=G/m

3. The attempt at a solution

homogeneous solution:

a^2+1/r a = 0 -> a = 0, -1/r

u1 = Ae^(-1)+B

try u2 = c r (as a constant B already exists as part of the solution, multiply by r)

u' = c u'' = 0

c/r = G/m

c = Gr/m

u2 = Gr^2/m

u = Ae^(-1)+B+Gr^2/m

Whereas the actual solution is

u = A Ln(r)+B+Gr^2/4m

Thanks for any help

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# Homework Help: Quick DE fix

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