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Math Help - Functions..

  1. #1
    Newbie Ai Ekio's Avatar
    Joined
    Sep 2008
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    11

    Functions..

    Hi.
    I'm having trouble with the following:

    If f(x)=|2x+1| and g(x)=x-4, find f(g(1)) and g(f(1))

    and

    Find the equation of the linear function f if f(1)=-1 and f(4)=8

    Thank you for looking it over,any help is greatly appreciated..
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  2. #2
    No one in Particular VonNemo19's Avatar
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    Detroit, MI
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    Quote Originally Posted by Ai Ekio View Post
    Hi.
    I'm having trouble with the following:

    If f(x)=|2x+1| and g(x)=x-4, find f(g(1)) and g(f(1))

    and

    Find the equation of the linear function f if f(1)=-1 and f(4)=8

    Thank you for looking it over,any help is greatly appreciated..
    f(g(x))=|2(x-4)+1|. Now evaluate at x=1.

    The other composite is similar.

    Oh. I just notice the second half of the problem. To find an equation to a line given 2 points in the plane, simply make use of the point-slope form of a line,

    (y_2-y_1)=m(x_2-x_1)

    where - in your case - m=\frac{-1-8}{1-4}
    Last edited by VonNemo19; December 10th 2009 at 08:27 AM.
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  3. #3
    Newbie Ai Ekio's Avatar
    Joined
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    Thank you. =)
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