# Derivative of a Function

• February 3rd 2009, 09:58 AM
cjh824
Derivative of a Function
I'm having trouble with the derivative of a function... :

4
____

square root(1-x)
• February 3rd 2009, 10:02 AM
Moo
Hello,
Quote:

Originally Posted by cjh824
I'm having trouble with the derivative of a function... :

4
____

square root(1-x)

$\frac{4}{\sqrt{1-x}}=4 \cdot (1-x)^{-1/2}$
Now just apply the chain rule, by using this derivative :
$(x^n)'=nx^{n-1}$
• February 3rd 2009, 10:21 AM
cjh824
Well we have to do it by using the definition of derivative. I got an answer of

2
___
(1-x)^3/2

but I don't think it's right.
• February 4th 2009, 02:10 AM
Moo
Quote:

Originally Posted by cjh824
Well we have to do it by using the definition of derivative. I got an answer of

2
___
(1-x)^3/2

but I don't think it's right.

Why do you think it's not right ? Because it's exactly the derivative !