# what is derivative of 1/(1+x)

• Aug 28th 2008, 05:16 AM
kevek
what is derivative of 1/(1+x)
what is derivative of 1/(1+x)?
• Aug 28th 2008, 05:30 AM
mr fantastic
Quote:

Originally Posted by kevek
what is derivative of 1/(1+x)?

$y = (ax + b)^n \Rightarrow \frac{dy}{dx} = a n (ax + b)^{n-1}$ is a standard result.
• Aug 28th 2008, 05:30 AM
moolimanj
Isnt this just $(1+x)^-1$ and hence the derivative is

$f'(x)=-1/(1+x)^-2$
• Aug 28th 2008, 05:32 AM
kevek
Thanks a lot.
• Aug 28th 2008, 05:35 AM
moolimanj
oooops - the -2 should be a 2 since i have put it in fraction form. If it wasnt in fraction form the answer would be - $1(1+x)^-2$ which is equal to $-1/(1+x)^2$