I'm trying to solve this limit without the use of L'Hospital, but I'm doing something wrong. The limit should be:
lim
My attempted proof:
\lim_{x\to 0}(\frac{e^{-x}-1}{x}) = \lim_{n\to \infty}(\frac{e^{-(\frac{1}{n})}-1}{\frac{1}{n}}) = \lim_{n\to \infty}(\frac{n \cdot ( e^{-(\frac{1}{n})}-1)}{1}) = \lim_{n\to \infty}(\frac{n \cdot ( e^{0}-1)}{1}) = \lim_{n\to \infty}(\frac{0}{1}) = 0
I assume the mistake is that I've used the continuity of the exp function.
Answer
A variation of Bernard's answer:
\frac{e^{-x}-1}x=\frac{1-e^x}{xe^x}=-\frac1{e^x}\cdot\frac{e^x-1}x\xrightarrow[x\to0]{}-\frac11\cdot(e^x)'_{x=0}=-e^0=-1
No comments:
Post a Comment