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Homework Help: Function and relations

  1. Feb 7, 2014 #1
    If f(x)= 2x+5, g(x)=0.5 and h(x)=3-1
    fg(x), gf(x), fh(3)

    fg(x)= 2(0.5x)+5
    fg(x)= x+5

    gf(x)= 0.5(2x+5)
    = x+2.5

    fh (x) =2(3-1)+5
    = 6-2+5
    = 4+5

    this last part of the question been puzzling me... could I get a little help plzzz :confused:
  2. jcsd
  3. Feb 7, 2014 #2


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    I'm going to guess from your solution you meant g(x)=0.5*x. If you really meant h(x)=3-1 then the last one is fine. But writing h(x)=3-1 is a little odd. Why not just write h(x)=2, or is it another typo?
    Last edited: Feb 7, 2014
  4. Feb 9, 2014 #3


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    Isn't the notation wrong? It looks like you want
    [itex](f \circ g)(x)[/itex], [itex](g \circ f)(x)[/itex] and [itex](f \circ h)(x)[/itex]
    (function composition)
    but it looks more like
    [itex](fg)(x)[/itex], [itex](gf)(x)[/itex] and [itex](fh)(x)[/itex]
    (combining functions by multiplication)
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