how about I do this

Factorise! $\displaystyle x^n-x=x(x^{n-1}-1)=x(x-1)(1+x+x^2+\cdots+x^{n-2}),$ the product of three terms which are obviously positive for $\displaystyle x\,>\,1.$

does this make sense?

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- Nov 21st 2009, 07:04 PM450081592
- Nov 22nd 2009, 06:27 AMMoo
Yes, and it's way better.