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I need help

  1. Apr 20, 2007 #1
    If x is positive and increasing at a rate of 2 units per second, at what rate is x^4 increasing when x=4?

    I don't even know how to start.
    If you can help me I would be greatful.
  2. jcsd
  3. Apr 20, 2007 #2


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    If x is increasing at the rate of 2 units/second then it must be increasing wrt some variable, call it t. So you are given dx(t)/dt=2 and x(t)=4. Now take the derivative of x(t)^4 and don't forget the chain rule.
  4. Apr 21, 2007 #3
    duh stupid me I know what to do thank you anyway
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