# Derivitive with ln - don't understand

#### zeion

1. Homework Statement

Differentiate the following:
y = ln(2x^2 - 2) / x^2 - 1

3. The Attempt at a Solution

The answer is y' = -ln(2x^2 - 2)(2x)(x^2 - 1)^-2 + 4x / 2x^2 - 2 (x^2 - 1)^-1

I understand all of it except 4x / 2x^2 - 2, how does ln(2x^2 - 2) derive into 4x / 2x^2 - 2?

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#### rock.freak667

Homework Helper
$$\frac{d}{dx}(ln(f(x))=\frac{f'(x)}{f(x)}$$

#### zeion

Oh okay, thanks, never seen that one before.

#### Hurkyl

Staff Emeritus
Gold Member
Oh okay, thanks, never seen that one before.
If you look closely, you'll notice that's just the chain rule....

Really? How?

#### mblack

To see how it is the chain rule, think about what the derivative of ln x is.

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