Expert: Paul Klarreich - 9/10/2009

Question
Hi Paul, I got a question for you, may you help me?
I need to know usages of function f(x) = ln(x) whose use this kind of function...and find out domain and image!! I'm really lost, your help will be welcome!

Thanks

Answer
Questioner: Gaston
Country: Argentina
Category: Calculus
Private: No
Subject: Domain and Image of a function
Question: Hi Paul, I got a question for you, may you help me?
I need to know usages of function f(x) = ln(x) whose use this kind of function...and find out domain and image!! I'm really lost, your help will be welcome!

Thanks
........................................

Domain of f(x) is the SET of possible inputs.  For f(x) = ln x, only positive numbers work, so that is the domain.

RANGE of f(x) is the SET of outputs, or results.  For f(x) = ln x, all real numbers can be results, so that is the domain.

We usually use IMAGE of a set, not image of a function.

Of course, the IMAGE of the DOMAIN is the RANGE.