PDA

View Full Version : Limes for an unknown solution


Zaare
Dec5-04, 12:08 PM
I have this eq.:
y'=\frac{1}{(1+x^2+y^2)}
I'm able to show that it has a unique solution for -\infty<x<\infty, and that the solution is an odd funktion.
What can I say about the limit of the solution as x grows towards infinity?

arildno
Dec5-04, 01:04 PM
For ALL x, you have:
0\leq{y'}\leq\frac{1}{1+x^{2}}

How does this help you?

Zaare
Dec5-04, 01:42 PM
Right! That means, y\leq{\arctan{x}}, therefor the limit of y is \leq{\pi/2}.
Thanks. I appreciate the help. :)