$e^x$ - natural exponential function
-$$\lim_{h \rightarrow 0} {{e^h-1} \over h}=1$$
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+$$\lim_{h \rightarrow 0} {{e^h-1} \over h}=1$$
+
+## 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 $f^{-1}: \mathbb{R}^+ \rightarrow \mathbb{R}, f^{-1}=log_ax$
+
+## Euler's number
+
+$$e= \lim_{n \rightarrow \infty} (1 + {1 \over n})^n$$
+
+## Literal equations
+
+_Literal equation_ - no numerical solutions
+
+## Exponential and logarithmic modelling
+
+$$A = A_0 e^{kt}$$
+
+where
+$A_0$ is initial value
+$t$ is time taken
+$k$ is a constant
+For continuous growth, $k > 0$
+For continuous decay, $k < 0$