Den naturlege eksponentialfunksjonen

Hans Georg Schaathun

September 2016

\(x = \ln y \quad \quad y > 0\)

\(y = \exp x \)

\(\ln 1 = 0\)\(\exp 0 = 1\)
\(\ln (xy) = \ln x + \ln y\)\(\exp (x+y) = (\exp x)(\exp y)\)
\(\ln \frac1x = - \ln x \)\(\exp (-x) = \frac1{\exp x} \)
\(\ln \frac xy = \ln x - \ln y \)\(\exp (x-y) = \frac{\exp x}{\exp y}\)
\(\ln (x^y) = y\ln x\)\((\exp x)^y = y\exp x\)

Definisjon

$$e = \exp 1 \approx 2{,}718$$

Definisjon: \(e = \exp 1\)

$$\exp x = \exp ( 1\cdot x) = (\exp 1)^x = e^x$$