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 Post subject: InequalitiesPosted: Thu, 21 Oct 2010 00:36:09 UTC
 S.O.S. Newbie

Joined: Thu, 21 Oct 2010 00:26:15 UTC
Posts: 2
Hi, I am looking at solving a rational inequality algebraically and the textbook says to multiply by the denominator squared, is this because squaring would remove the effect of a negative value of x and hence a change in sign. Thanks

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 Post subject: Re: InequalitiesPosted: Thu, 21 Oct 2010 04:25:24 UTC
 S.O.S. Oldtimer

Joined: Fri, 10 Oct 2008 15:35:23 UTC
Posts: 179
Location: Clarksville, ARkansas
kej wrote:
Hi, I am looking at solving a rational inequality algebraically and the textbook says to multiply by the denominator squared, is this because squaring would remove the effect of a negative value of x and hence a change in sign. Thanks

Yes, that's essentially the reason. More precisely, it's because the denominator may be negative for some values of x. However, if your denominator is a perfect square, you could simply multiply both sides by the denominator without further squaring it.

There are other methods which are also designed to avoid multiplying by the denominator, when it's not clearly non-negative.

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 Post subject: Posted: Fri, 22 Oct 2010 18:12:26 UTC
 S.O.S. Newbie

Joined: Thu, 21 Oct 2010 00:26:15 UTC
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