Step one: What values of x can we plug into the equation and still get a solution? Included with this question is: What values of x can we not plug into the equation to get a solution?

Since the function is log, we know that we cannot take the log (ln in this case) of a negative number or of 0, so the term inside the function must be >0.

Step two: Find these values of x.

The term inside the log is (x + 1), so:

(x + 1) > 0

x > -1

That is your domain, which can be written as:

D = (-1,inf)