From 77db891721cf67f5118278e2571c653fb143e56f Mon Sep 17 00:00:00 2001 From: Andrew Lorimer Date: Tue, 5 Mar 2019 12:59:08 +1100 Subject: [PATCH] [methods] logarithm laws --- methods/stuff.md | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/methods/stuff.md b/methods/stuff.md index 0424391..1cbb98b 100644 --- a/methods/stuff.md +++ b/methods/stuff.md @@ -40,4 +40,16 @@ If $a<1, \quad \log_{b} a < 0$ (flip inequality operator) $e^x$ - natural exponential function -$$\lim_{h \rightarrow 0} {{e^h-1} \over h}=1$$ \ No newline at end of file +$$\lim_{h \rightarrow 0} {{e^h-1} \over h}=1$$ + +## Logarithm laws + +$\log_a(mn) = \log_am + \log_an$ +$\log_a({m \over n}) = \log_am - \log_an$ +$\log_a(m^p) = p\log_am$ +$\log_a(m^{-1}) = -\log_am$ +$\log_a1 = 0$ and $\log_aa = 1$ + +## Inverse functions + +Inverse of $f: \mathbb{R} \rightarrow \mathbb{R}, f(x)=a^x$ is $f^{-1}: \mathbb{R}^+ \rightarrow \mathbb{R}, f^{-1}=log_ax$ -- 2.43.2