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Topic: math problems - help
Replies: 5   Last Post: Oct 4, 2013 7:14 PM

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wilson

Posts: 4
Registered: 9/27/12
Re: math problems - help
Posted: Oct 4, 2013 12:17 AM
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On Thu, 03 Oct 2013 21:05:50 -0400, stony <x@x.com> wrote:

> Hi, I come here once in a while to get some confusions cleared up or
> get hints on how to solve something. I teach my daughter who is in
> middle school and we come across some problems that stump us.
> Any hints would be appreciate.
>
> The one below, I am missing something in terms of simplifying or some
> series or something. Basically, I have tried combining all the terms
> after expanding it and could not got to a solution that would simplify
> it to prove. It stays in a the expanded form pretty much.
>
> Prove that:
>
> ((1/(a^2+1)) + ((1/(b^2+1)) + ((1/(c^2+1)) <= 1/2
>
> <= - less than or equal to 1/2
>
> I have grouped them together in several ways, but not come close to
> simplifying the expanded equation. I thought I could be missing a
> simple clue, but cannot come up with it for the past 2 hours. Its not
> homework, but practice which she could not do it and I tried it but
> have not been able to simplify. Thannks for the help.
>
> s



--
One reason you might be having a problem is that there is no restriction
on the values of a, b, and c. If they are all zero, the inequality is
false. Now, assume a, b, and c are all larger than three. Then the
inequality is true. (Why?) Inbetween 0 and 3 the inequality becomes
dependent upon the relationships between a, b, and c.

Looks to me like a very poor problem to assign to a college student let
alone one in middle school.



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