1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Simple derivative check

  1. Sep 29, 2009 #1
    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. jcsd
  3. Sep 29, 2009 #2
    If I'm reading your problem correct, your answer seems more correct than his.

    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"? :)
  4. Sep 29, 2009 #3


    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
  5. Sep 29, 2009 #4
    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!
  6. Jun 26, 2010 #5
    I got 1/[(2-x)^2]
  7. Jun 27, 2010 #6


    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?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook