Okay I'm a little embarassed to ask this, since I'm taking a class where we're solving non-homogeneous partial diff. equations all over the place, but when I'm faced with this simple ODE, I can't remember how to solve it :

y''

 

lol. so easy bro! c'mon man, I'll give ya a moment to think about it. I swear you'll kick yourself in the butt if I just up and give ya the answer.

 

Lay it on me dude, I can't think any more today...

 

haha, I JUST asked this question, I think, a few weeks ago.

 

Tedow, you can call me an asshole if you want. I was just trying to jog your memory... and ok... mess with ya a lil bit. sorry bro, I have no friggin clue! I got my degree in English. jeez, I suck. sorry man.

 

[QUOTE]Originally posted by tritium_pie
Tedow, you can call me an asshole if you want.

 

Did you get an answer?

 

This is a second-order linear ODE with the independent variable (y) missing, so:

Let u = y'

u' = y"

u' + 1/r u = 0

This is a first-order linear ODE, so you use an integrating factor:

e^(integral(1/r)) = e^ln

 

Sweet, that makes sense, though I would never have guessed to use that approach (getting (ru)'). I knew you'd chime in with the answer sooner or later...thanks, Magician .

 

My pleasure.

I taught differential equations and linear algebra last semester, so the ideas are still somewhat fresh in my mind