What is the domain and range of ln(x-1)?

1 Answer
Mar 3, 2018

x>1 (domain), yinRR (range)

Explanation:

The domain of a function is the set of all possible x values that it is defined for, and the range is the set of all possible y values. To make this more concrete, I'll rewrite this as:

y=ln(x-1)

Domain: The function lnx is defined only for all positive numbers. This means the value we're taking the natural log (ln) of (x-1) has to be greater than 0.

Our inequality is as follows:

x-1>0

Adding 1 to both sides, we get:

x>1 as our domain.

To understand the range, let's graph the function y=ln(x-1).

graph{ln(x-1) [-10, 10, -5, 5]}

When we look at our graph, there are no discontinuities in it, thus our range is:

yinRR, which just means y is a member of the real numbers or y can take on any value.