A simple ln differentiation question

Hi

I'm somewhat embarassed to be asking such a simple question but hopefully someone would be kind enough to help me out.

I've been asked to find the first and second derivatives of **A = ln x** so I got the following, which agreed with the answers given:

**A' = 1/x**

However, my confusion is with the second derivative. I prefer to use **x^-1 **rather than **1/x**. Using **x^-1** would give me **-1*x^-1-1**:

**A'' = -x^-2** or **-1/x^2**

The answer given is **1/x^2 ** (ie positive, rather than the negative answer I get).

Would somebody be kind enough to tell me which is correct and, if I'm wrong, please explain where I've gone wrong. Thanks very much.

Dave.