# Advice for derievative

1. Aug 19, 2008

### babypudding

1. The problem statement, all variables and given/known data

Find dc/dp and dc/dq.

2. Relevant equations

c= (2p/q)-1/2

3. The attempt at a solution

I just want to make if I'm right. I got...
dc/dp = (2/q)-1/2

dc/dq = [-2p/(q^2)] -1/2

Thanks.

2. Aug 19, 2008

### happyg1

Re: derievative

Hi,
There is an error in your use of the chain rule:
$$\frac{dc}{dp}=-\frac{1}{2}\left(\frac{2p}{q}\right)^{-\frac{3}{2}}\cdot\left(\frac{2q-0}{q^2}\right)$$
then simplify.

Same thing for dc/dq:
$$\frac{dc}{dq}=-\frac{1}{2}\left(\frac{2p}{q}\right)^{-\frac{3}{2}}\cdot\left(\frac{0-2p}{q^2}\right)$$
then simplify.

Last edited: Aug 19, 2008
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