# Simple derivative check

1. Sep 29, 2009

### hanelliot

1. The problem statement, all variables and given/known data
derivative of x*sqrt[x/(2-x)]

2. Relevant equations

3. The attempt at a solution
my friend got 1/(2-x) and I got {-(x-3)*[-x/(x-2)]^3/2}/x. Who's right?

2. Sep 29, 2009

### mrkuo

I've got [(sqrt x)*(3-x)]/[(2-x)^(3/2)] which should be the same answer in a more simplified format.

Now my question is: what kind of class are you taking where you would call this a "simple derivative"? :)

3. Sep 29, 2009

### Staff: Mentor

I don't think either of you is correct, and your friend is very far off. Your answer doesn't appear to be correct, but at least I can see how you are thinking. To do this problem you will have to apply, in this order,
1. the product rule,
2. the chain rule,
3. the quotient rule

4. Sep 29, 2009

### hanelliot

multivariable calculus II, I've been away from math for a long time and this is embarrassing.. anyways, ur answer = mine (plugged in few numbers to confirm), thanks all!

5. Jun 26, 2010

### lmnop

I got 1/[(2-x)^2]

6. Jun 27, 2010

### Staff: Mentor

First off, this thread is almost 9 months old.

Second, my answer agrees exactly with mrkuo's answer. lmnop, how did you get your answer?