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Chain/Product rule question

  1. Dec 14, 2009 #1
    Ok, I have having a very hard time finding the derivative of this, I have no clue how to do the set up.

    x^2(sqrt(9-x^2))

    (sorry it's written like that I just have no clue how to type it normally)
    So the problem I am having is When do I use the chain rule, and the product rule cohesively, I have the answer to the problem but it does me no good because I cannot solve it.
    Thanks in advance.
     
  2. jcsd
  3. Dec 14, 2009 #2
    Any help would be greatly appreciated, I have been pulling my hair out for 2 hours :(
     
  4. Dec 15, 2009 #3

    Mark44

    Staff: Mentor

    You have a product, so you need to use the product rule first. One of the factors is a composite function, so after you use the product rule, you'll need to use the chain rule.

    Don't try to do everything at once.

    d/dx[x^2 * (9 - x^2)^(1/2)] = x^2 * d/dx[(9 - x^2)^(1/2)] + 2x * (9 - x^2)^(1/2) = ?
     
  5. Dec 15, 2009 #4
    Thank you so much that cleared it right up for me :)
     
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