I'm trying to prove: lim without use L'Hospital and derivate, because I still do not define derived from the logarithm, is there any way to prove it by the definition epsilon-delta? So far I have only defined \log as the inverse function of a^{x} and particular case a = e although the latter is proposed very weak, it may be improved later using integrals, some help thanks in advance.
Answer
\lim_{x \rightarrow 0} \frac {ln(1+x)} x = \lim_{x \rightarrow 0} \frac 1 x ln(1+x) = \lim_{x \rightarrow 0} ln((1+x)^{\frac 1 x}) = ln(\lim_{x \rightarrow 0} (1+x)^{\frac 1 x}) = ln(e) = 1
We use the fact that a ln(b) = ln(b^a)
Edit: Based on comments, I added one last step before "ln(e)". This is to showcase that limits have the property that \lim_{x \rightarrow x_0} f(g(x)) = f(\lim_{x \rightarrow x_0} g(x) ) provided that \lim_{x \rightarrow x_0} g(x) = L, L \in \mathbb R and that f is continuous at x=L
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