# Derivative help?

• November 11th 2012, 03:45 PM
camjenson
Derivative help?
Hello! Can anybody help me and tell me what the derivative of (6x)^-2 is? Thanks! I'm having a brain fart :(
• November 11th 2012, 03:58 PM
Plato
Re: Derivative help?
Quote:

Originally Posted by camjenson
Hello! Can anybody help me and tell me what the derivative of (6x)^-2 is?

$D_x \left[ {\left( {6x} \right)^{ - 2} } \right] = - 12\left( {6x} \right)^{ - 3}$.

BTW: Your brain cannot to that.
• November 11th 2012, 04:10 PM
Soroban
Re: Derivative help?
Hello, camjenson!

Quote:

Can anybody tell me what the derivative of $(6x)^{-2}$ is?

If you can't handle the Chain Rule,
. . you can write: . $y \;=\;(6x)^{-2} \;=\;6^{-2}x^{-2} \;=\;\tfrac{1}{36}x^{-2}$

Then: . $y' \;=\;\tfrac{1}{36}\left(\text{-}2x^{-3}\right) \;=\;-\tfrac{1}{18}x^{-3} \;=\;-\frac{1}{18x^3}$