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Math Help - Inverses Graph #4

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    Inverses Graph #4

    Thanks!!

    Looking for a quick way to find f^-1(#) if asked to do so.
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by qbkr21 View Post
    Thanks!!

    Looking for a quick way to find f^-1(#) if asked to do so.
    remember, if f(x) = \# then f^{-1}(\#) = x

    so when they ask for, say, f^{-1}(2), they are looking for the x value such that f(x) = 2

    so find a point on the graph where y = 2 and the corresponding x value is f^{-1}(2)
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    Re:

    When you mean f(x) do mean f(x) is the same thing as Y?
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by qbkr21 View Post
    When you mean f(x) do mean f(x) is the same thing as Y?
    yes, y = f(x), right?


    so they ask you to find f^{-1}(2), you don't know what it is, so equate it to a variable. this variable can be anything, but i chose x because the answer will be an x-value

    So let f^{-1}(2) = x

    \Rightarrow f \left(f^{-1}(2) \right) = f(x)

    \Rightarrow 2 = f(x)

    So now we need to know what x has to be so that f(x), that is, the correspoding y-value for x, is 2
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    Re:

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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by qbkr21 View Post
    0
    yes
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    Re:

    Jhevon could I just draw a horizontal line where y = #, and those spots that go through y = # would be f^-1(x)?

    Thanks!!
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    Quote Originally Posted by qbkr21 View Post
    Jhevon could I just draw a horizontal line where y = #, and those spots that go through y = # would be f^-1(x)?

    Thanks!!
    the x-values for the points where the horizontal line cuts the graph is f^-1(#)
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    Re:

    Would the answer to letter D be about -1.8
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    Quote Originally Posted by qbkr21 View Post
    Would the answer to letter D be about -1.8
    yea, roughly -1.7,-1.8 around there. -1.8 is fine. don't think your professor will be too hard on you by being off by 0.1 since the grid is not accurate enough to be exact
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