Chapter 5 - Logarithmic, Exponential, and Other Transcendental Functions - 5.1 Exercises - Page 325: 21

$\ln x+\ln y-\ln z$

See Th.5.2. Property $2$ : $\ln(ab)=\ln a + \ln b$ Property 4 : $\displaystyle \ln(\frac{a}{b})=\ln a - \ln b$ $\displaystyle \ln(\frac{xy}{z})$ = ... property 4... $=\ln(xy)-\ln z$= ... property 2... $= \ln x+\ln y-\ln z$