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Slope of graph?

  • 21-05-2012 7:20pm
    #1
    DEVEREUX
    Registered Users, Registered Users 2 Posts: 541 ✭✭✭


    I have an exam looming and have hit a speed bump with the following question

    find slope of graph y = 1/x when x = 2

    What im getting is

    1/x = x^-1

    giving me

    2^-1 = - 1/2

    Above makes sense to me but in the answer sheet for this particular question the lecturer has the answer as -1/4 ????
    Help appreciated, thanks.


Comments

  • #2
    **Timbuk2**
    Moderators, Education Moderators, Motoring & Transport Moderators Posts: 7,396 Mod ✭✭✭✭**Timbuk2**


    You have [latex]y = x^{-1}[/latex]

    The slope is the derivative, i.e. [latex]\frac{dy}{dx} = \frac{d}{dx}x^{-1} = -\frac{1}{x^2}[/latex]

    At x=2, this is -1/4


  • #3
    DEVEREUX
    Registered Users, Registered Users 2 Posts: 541 ✭✭✭DEVEREUX


    **Timbuk2** wrote: »
    You have [latex]y = x^{-1}[/latex]

    The slope is the derivative, i.e. [latex]\frac{dy}{dx} = \frac{d}{dx}x^{-1} = -\frac{1}{x^2}[/latex]

    At x=2, this is -1/4

    Thanks for that.


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