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Inverse function

  1. Nov 22, 2009 #1
    1. The problem statement, all variables and given/known data
    if g(5)=-2, then g^-1(-2)=?

    2. Relevant equations


    3. The attempt at a solution

    i can't remember how to work inverse functions when there is no variable
    i think its g^-1(-2)=5 but it could be g^-1(-2)=-2
  2. jcsd
  3. Nov 22, 2009 #2


    Staff: Mentor

    The most fundamental concept about a function that has an inverse is that if a = f(b),
    then b = f-1(a). Use this concept in your problem.

    In different words, f maps b to a, so f-1 is a pairing in the other direction; IOW, f-1 maps a to b.
  4. Nov 22, 2009 #3


    User Avatar
    Homework Helper

    Think about these (very loose, incredibly non-mathematical) formulations of inverse functions.

    "The inverse function reverses what the original function does."

    "If you start at an x, apply the function to get a y, then apply the inverse function, you get back to x."

    Does either of these help?
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