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Topic: Probability of success calculation
Replies: 17   Last Post: Jun 2, 2011 2:49 PM

 Messages: [ Previous | Next ]
 Brian M. Scott Posts: 1,289 Registered: 12/6/04
Re: As x approaches 5
Posted: Jun 1, 2011 4:18 PM

On Wed, 01 Jun 2011 12:35:03 -0700, Alexandros Bantis
<ambantis@gmail.com> wrote in
<news:94nij9F5phU1@mid.individual.net> in

[...]

> I'm curious. How is it possible that the function changes
> a fundamental property [f(5) == undefined versus f(5) =
> 1/6] when all I've done is multiply by 1. I see that
> this has happened, but intuitively it feels odd.

It didn't change when you multiplied by 1: the change
occurred when you cancelled x - 5. After the multiplication

(x - 5) / [(x - 5) sqrt(x + 4) + 3],

which is exactly equal to f and in particular undefined at
x = 5. In other words,

f(x) = (1 / [sqrt(x + 4) + 3]) [(x - 5) / (x - 5)],

but this is equal to 1 / [sqrt(x + 4) + 3] only where
(x - 5) / (x - 5) = 1, i.e., where it's actually defined.

Brian

Date Subject Author
5/11/11 priyatosh
5/11/11 Barb Knox
5/12/11 priyatosh
5/12/11 Pubkeybreaker
5/12/11 The Qurqirish Dragon
6/1/11 Alexandros Bantis
6/1/11 Brian M. Scott
6/1/11 Alexandros Bantis
6/1/11 Brian M. Scott
6/1/11 JimmyJohn
6/2/11 Brian M. Scott
6/1/11 Frederick Williams
6/1/11 JimmyJohn
6/1/11 Barb Knox
6/1/11 Alexandros Bantis
6/1/11 Barb Knox
6/2/11 Frederick Williams
6/2/11 Virgil