How can we prove that \frac{x-1}{x-2} < 1 for x < 0?

doubleaxel195
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Homework Statement


I just want to show that given x<0, \frac{x-1}{x-2} &lt;1.


The Attempt at a Solution



I don't know why I am having trouble with this! I feel like this is so easy!

So if x<0, then we know x-1&lt;-1, x-2&lt;-2. So
\frac{-1}{2}&lt;\frac{1}{x-2} and \frac{x-1}{x-2}&lt;\frac{-1}{x-2}.

I can't seem to get a good upper bound on \frac{1}{x-2} that makes the entire thing less than one. Am I doing something illegal? Because now it looks like I should want to get\frac{1}{x-2} &lt;-1 to make it all less than one, but clearly that is not true.
 
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doubleaxel195 said:

Homework Statement


I just want to show that given x<0, \frac{x-1}{x-2} &lt;1.

The Attempt at a Solution



I don't know why I am having trouble with this! I feel like this is so easy!

So if x<0, then we know x-1&lt;-1, x-2&lt;-2. So
\frac{-1}{2}&lt;\frac{1}{x-2} and \frac{x-1}{x-2}&lt;\frac{-1}{x-2}.

I can't seem to get a good upper bound on \frac{1}{x-2} that makes the entire thing less than one. Am I doing something illegal? Because now it looks like I should want to get\frac{1}{x-2} &lt;-1 to make it all less than one, but clearly that is not true.
\displaystyle \frac{x-1}{x-2}=\frac{x-2+1}{x-2}=1+\frac{1}{x-2}

Can you show that 1/(x-2) < 0 ?
 
Yes I can. Thank you so much! Was I doing anything illegal or just picking bad bounds? I can't seem to find a mistake in what I was doing before.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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