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Derivative question help!

  1. Oct 21, 2012 #1
    1. The problem statement, all variables and given/known data

    Consider the following function of variable r, for r greater or equal to 0.
    y(r)=(r^2-8r)exp(-r)

    1. Find the value of the first derivative at r=8.00
    2. Find the value of the second derivative at r=8.00
    3. Find the value of r where y takes its meinimum value in the r is greater or equal to 0 interval
    4. Find the value of r where y takes its maximum value in the r is greater or equal to 0 interval


    Please explain how you do it too! I am so lost :(


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 21, 2012 #2
    looks like you need to take the derivative of the function y(r) and then plug in the values
     
  4. Oct 21, 2012 #3
    I know but I have no idea how to do that, im new to physics so this is all new to me.
     
  5. Oct 21, 2012 #4
    This has nothing to do with physics and everything to do with calculus. Have you studied it and have you studied derivatives in particular?
     
  6. Oct 21, 2012 #5
    I have not learned anything about derivatives. My Physics Professor just decides to assign us 3 derivative problems over the weekend on MasteringPhysics :(
     
  7. Oct 21, 2012 #6
    I am not sure what this could possibly mean. If you have not taken any calculus, then you won't be able to solve this problem.
     
  8. Oct 21, 2012 #7
    Is calculus a prerequisite for the physics course? Are you taking algebra based physics or calculus based physics?
     
  9. Oct 21, 2012 #8

    Mark44

    Staff: Mentor

    The OP has not shown any effort. I am locking this thread.
     
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