Possible Duplicate:
Natural Logarithm and Integral Properties
I was asked to prove that ln(xy) = ln x + ln y
using the integral definition. While I'm not asking for any answers on the proof, I was wondering how to interpret and set-up this proof using the "integral definition" (As I am unsure what that means.)
EDIT
And to prove that ln(x/y) = ln x - ln y
Is it right to say this?
$\ln(\frac{x}{y})=\int_1^{\frac{x}{y}} \frac{dt}{t}=\int_1^x \frac{dt}{t}-\int_x^{\frac{x}{y}}\frac{dt}{t}.$