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Homework Help: Prove that two equations are inverses of each other.

  1. Aug 7, 2012 #1
    1. The problem statement, all variables and given/known data
    f(x) = 9-x^2, x ≥ 0. g(x) = sqrt (9-x)

    2. Relevant equations
    Two equations are inverses of each other if f(g(x)) = g(f(x)) = x.

    3. The attempt at a solution

    f(g(x)) = 9 - (sqrt (9-x))^2

    = 9 - (9-x)
     
  2. jcsd
  3. Aug 7, 2012 #2
    Open the brackets?
     
  4. Aug 7, 2012 #3
    Hmm?
     
  5. Aug 7, 2012 #4

    Mark44

    Staff: Mentor

    So close! Simplify the above.

    Don't forget that you also have to show that g(f(x)) = x.
     
  6. Aug 8, 2012 #5

    Mark44

    Staff: Mentor

    BTW, we don't normally say that equations are inverses of each other - we say that functions are inverses of each other.
     
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