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Homework Help: Tangent Line

  1. Dec 16, 2008 #1
    1. The problem statement, all variables and given/known data
    Find an equation for the line tangent to to the graph of f^-1 at the pt (3,1) if f(x)=x^3+2x^2-x+1



    2. Relevant equations



    3. The attempt at a solution
    I used the Inverse Function Thm
    1/(3x^2+4x)
    Now do I plug in 3 to this to find slope?
    1/21
    y-1=1/21(x-3)
    y-1=1/21x-1/7
    y=1/21x+6/7
     
  2. jcsd
  3. Dec 17, 2008 #2
    state the inverse function thm.
    what is (3,1) a point of?

    also, i think you are mixing up x's. if you look at f^-1 as a function of x, these x's are really values (or y's) of f(x)

    i hope you understand this; i'm afraid i've been a bit convoluted.
     
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