The other day we were given a practice AB calculus exam (since I am in BC, we have already covered all of AB), and I had a quick question from it. I probably knew the answer to this, but forgot it, so if someone could give me a refresher by answering this question, that would be much appreciated.

Question

anonymous · Answer

Why do the absolute values on ln$$\left[ x^2-1 \right]$$ go away when you derive it?

anonymous · Answer

$$\ln \left[ x^2-1 \right]$$

anonymous · Answer

This was a multiple choice question, and they just wanted me to derive f(x). The answer is 2x/(x^2-1)

anonymous · Answer

the derivative of 
$$\ln(f(x))$$ is, by the chain rule 
$$\frac{f'(x)}{f(x)}$$

anonymous · Answer

Sorry, I was having wifi issues. I get it now! Thanks!!

anonymous · Answer

So just completely ignore the absolute values?