# Derivative

• March 9th 2008, 06:57 PM
BKennedy
Derivative
Can anyone help me with the derivative of 5xArctan(2x)???

Thank you!!
• March 9th 2008, 07:04 PM
TheEmptySet
Quote:

Originally Posted by BKennedy
Can anyone help me with the derivative of 5xArctan(2x)???

Thank you!!

Use the product rule

let

$f(x)=x$ and $g(x)=\tan^{-1}2x$ then
$f'(x)=1$ and $g'(x)=\frac{2}{1+4x^2}$

by the product rule we get...

$\frac{d}{dx}(fg(x))=f'(x)g(x)+f(x)g'(x)=1 \cdot \tan^{-1}(2x)+x \cdot \frac{2}{1+4x^2}$

Just simplify from there