Friday, October 14, 2016

calculus - Limit limxto1fraclogxx1 without L'Hôpital




I was wondering if it's possible to identify this limit without using L'Hôpital's Rule:

lim


Answer



In THIS ANSWER and THIS ONE I showed, without the use of calculus, that the logarithm function satisfies the inequalities



\frac{x-1}{x}\le \log(x)\le x-1



Therefore, we can write for x>1



\frac1x \le \frac{\log(x)}{x-1}\le 1




and for x<1



1 \le \frac{\log(x)}{x-1}\le \frac1x



whereupon applying the squeeze theorem yields the result 1.


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