# How do you find the derivative of f(x) = -15 / (4x + 5)^4 using the chain rule?

##### 1 Answer
Nov 17, 2015

I prefer to rewrite the function as $f \left(x\right) = - 15 {\left(4 x + 5\right)}^{-} 4$

#### Explanation:

Then $f ' \left(x\right) = 60 {\left(4 x + 5\right)}^{-} 5 \frac{d}{\mathrm{dx}} \left(4 x + 5\right)$

$= 60 {\left(4 x + 5\right)}^{-} 5 \left(4\right)$

$= \frac{240}{4 x + 5} ^ 5$