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Homework Help: Help finding slope of curve

  1. Feb 26, 2014 #1
    Problem statement
    F(x)= x^2-3x

    Revelant equation
    Lim f(a+h)-f(a)/ (h) As h approaches 0

    Attempt at a solution ImageUploadedByPhysics Forums1393450782.190789.jpg

    Now this is where I get stuck.. Because usually you have a h that cancels out and then you have something in the form of (h+a) that can be used to determine the slope.. What do I do next??
  2. jcsd
  3. Feb 26, 2014 #2


    Staff: Mentor

    What you got for f(1 + h) is wrong. f(1 + h) = (1 + h)2 - 3(1 + h).

    Also, you don't seem to use "=" consistently in your work. You have
    ##lim_{h \to 0} = ##, following by the thing you're taking the limit of, which is incorrect. You also don't connect the expressions you're doing algebra on with an equal sign, nor do you include the "lim" notation. "lim" should go away only when you actually take the limit, not before.
  4. Feb 26, 2014 #3


    User Avatar
    Homework Helper

    You have made a calculation error:

    [tex]F(1 + h) - F(1) = (1 + h)^2 - 3(1 + h) + 2[/tex]
    and not [itex](1 + h)^2 + 2[/itex] as you have.
  5. Feb 26, 2014 #4

    I see my error now thank you!
  6. Feb 26, 2014 #5

    Thank you for your comments. How do I do the lim notations on physics forum?
  7. Feb 26, 2014 #6


    User Avatar
    Homework Helper

    Code (Text):

    [tex]\lim_{h \to 0}[/tex]
    \lim_{h \to 0}
  8. Feb 26, 2014 #7

    Is there a guide where I can find all of these notations?
  9. Feb 26, 2014 #8


    User Avatar
    Homework Helper

    See here.
  10. Feb 26, 2014 #9

    Thank you. You have been a great help!
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