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Math Help - Compositions of functions

  1. #1
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    Compositions of functions

    How to finde the following:
    x, if f(x) = 0
    h(6) if h(x) = square root(18 - 4x)
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  2. #2
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    Quote Originally Posted by Snowboarder View Post
    How to finde the following:
    x, if f(x) = 0 Mr F says: This makes no sense. What is the rule for f(x)?

    h(6) if h(x) = square root(18 - 4x) Mr F says: Substitute x = 6 into the given rule. You get an answer that's not real.
    ..
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  3. #3
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    Quote Originally Posted by Snowboarder View Post
    How to finde the following:
    x, if f(x) = 0
    h(6) if h(x) = square root(18 - 4x)
    Let's assume f(x) = h(x)

    h(x) = \sqrt{18-4x}

    h(6) = \sqrt{18-4(6)} \Rightarrow \sqrt{-24} = 2i\sqrt{6}

    h(x) = 0

    \sqrt{18-4x} = 0

    18-4x = 0

    4x=18

    x=\frac{9}{2}
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