Q&A #1530

Teachers' Lounge Discussion: Factoring out -1 in algebraic expressions

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From: Loyd

To: Teacher2Teacher Public Discussion
Date: 2003030307:55:33
Subject: Re: x squared minus one divided by one minus x

On 2003030123:23:15, Anonymous wrote: > >How do I do this? >so far I've got (x+1)(x-1)/-(x-1) >cancel out the x-1 >leaving me with x+2/-1 >the answer is -(x+1) but why why why??? > Replace "leaving me with x+2/-1" to x+1/-1 The last expression is equal to -(x+1). A fraction has three signs: +a +--- You can change any two of them and the fraction will still be +b equavilent to the original. Thus: (x+1)/-1 can be rewritten as: + (x-1) + ----- which is equal to -1 -(x-1) + ----- which is equal to +1 -(x-1)

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