# Math Help - Derivative of a Function

1. ## Derivative of a Function

I'm having trouble with the derivative of a function... :

4
____

square root(1-x)

2. Hello,
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 :
$(x^n)'=nx^{n-1}$

3. 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.

4. 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 !