Ordinary differential equation question

real analyst
Messages
10
Reaction score
0

Homework Statement



What is the general solution to the following ODE

F=X''m where F and m are both constants

Homework Equations





The Attempt at a Solution



I got X=(k/2)t^2 + C

I got this from F/M being just another constant K, and X'' being (d^2 X)/(dt^2) so you just integrate k twice with respect to t, the first giving kt, and the second giving (k/2)t^2 + C. Is this correct?
 
Physics news on Phys.org
almost but not quite,

assuming m != 0, F = X''m => F/m = X'' , so X' = (F/m)x + C, say k = F/m, so

X' = kx + C, now integrate again,

X = kx^2/2 + Cx + D
 
yep, stupid mistake. thanks alot!
 
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