Seperable Differential Equations, Multiplicative Constant Confusion Help Clarify

danerape
Messages
31
Reaction score
0
I curiously never had a problem solving Seperable Equations in the Seperable Equations chapter of the Boyce/Diprima book. I am the kind of person who likes to do things the long way, and encountered a problem solving for an Integrating Factor(Linear ODE, NOT EXACT) the long proofy way. I tend not to use the (e^(INT)p(x)dx) formula. Formulas are too easy to forget.

In solving for the integrating factor, I came upon an easy seperable equation of course! I split this one up a little differently than usually, still correctly I think? I came up with an answer that differs from the formula approach.

Is the 1/3 absorbed by the constant or something?
PDF ATTACHED

Thanks,

Dane
 

Attachments

Physics news on Phys.org


Yes you could say they are equal. I prefer to say they are the same thing - and if you wrote 15K3 instead of K1 it would the same thing. At this stage they are both arbitrary, in a sense they are not anything. When you make conform to an initial condition you will get the same result from either of them.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top