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Homework Help: Find (f^-1) (a) if f(x)

  1. Dec 1, 2008 #1
    1. The problem statement, all variables and given/known data
    Find (f^-1) (a) if f(x) = sqrt of (x^3+x^2+x+2) and a = 4?


    2. Relevant equations
    Find (f ^-1) (a) = 1/ f ^1( f ^-1(a))


    3. The attempt at a solution
    Take Derivative
    1/2(x^3+x^2+x+2)^-(1/2)
    do I need to do chain rule?
    I am lost
    this problem can help me pass the class
    plz help
     
  2. jcsd
  3. Dec 1, 2008 #2

    Mark44

    Staff: Mentor

    This problem has nothing to do with derivatives or the chain rule or reciprocals.
    [tex]x = f^{-1}(a) \iff a = f(x)[/tex]

    So basically, what you need to do is solve the equation [tex]4 = \sqrt{x^3 + x^2 + x + 2}[/tex]

    BTW, this doesn't make any sense at all: (f ^-1) (a) = 1/ f ^1( f ^-1(a))
     
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