Derivative of Natural Logarithm of a x

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Theorem

Let $\ln x$ be the natural logarithm function.

Then:

$\map {\dfrac \d {\d x} } {\ln a x} = \dfrac 1 x$


Proof

\(\ds \map {\dfrac \d {\d x} } {\ln a x}\) \(=\) \(\ds a \map {\dfrac \d {\d \paren {a x} } } {\ln a x}\) Derivative of Function of Constant Multiple
\(\ds \) \(=\) \(\ds a \dfrac 1 {a x}\) Derivative of Natural Logarithm
\(\ds \) \(=\) \(\ds \dfrac 1 x\)