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Homework Help: F(x) substitution

  1. Aug 29, 2008 #1
    1. The problem statement, all variables and given/known data
    f(h+1)-f(h)/h. If f(x)=1/x, simplify.


    2. Relevant equations



    3. The attempt at a solution
    1/x+1-(1/x)/h

    is the answer 1/h? I am not sure if i substituted this correctly or if I solved this right.
    I put 1/x in everywhere there was a f(h).
     
  2. jcsd
  3. Aug 29, 2008 #2

    Dick

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    If f(x)=1/x, then f(h+1)=1/(h+1), f(5)=1/5. Etc. x is only a dummy variable.
     
  4. Aug 29, 2008 #3
    Incorrect.

    f(h+1)=1/(h+1)

    f(h)=1/h

    [f(h+1)-f(h)]/h

    [1/(h+1)-1/h]/h

    Continue.
     
  5. Aug 29, 2008 #4
    so it should have been (1/x+1 -1/x)/h
    dealing with the numerator first, I bring the terms to a common denominator..
    (x-x+1/x^2+x)/h.
    i multiply the numerator by 1/h and get..
    1/hx^2+hx
    is that right?
     
  6. Aug 29, 2008 #5

    Dick

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    You aren't listening. There are NO x's in (f(h+1)-f(h))/h. Reread the previous posts. By the way, are you sure the problem isn't (f(h+1)-f(1))/h??
     
    Last edited: Aug 29, 2008
  7. Aug 29, 2008 #6
    Okay, I can see that now. Thanks.
     
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