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    http://www.examsolutions.net/a-level...e/paper.php#Q7

    i idon't quite understand how to do question 7 part b
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    ff(0) is just f[f(0)]. Find f(0) first, which in this case is 5. Now find f(5) on this same graph.
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    Which is 3
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    (Original post by meowgoesthedog)
    ff(0) is just f[f(0)]. Find f(0) first, which in this case is 5. Now find f(5) on this same graph.
    Spoiler:
    Show
    Which is 3
    i don't understand where the 5 comes from how can one know it's 5?
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    (Original post by bigdonger)
    i don't understand where the 5 comes from how can one know it's 5?
    I see is as the function being made up of two straight lines for 2 separate ranges of x values. So when -2<x<2 f(x) = 2.5x + 5, but when 2<x<6 f(x) = x-2. Since -2<0<2 then it lies on the first line. f(0)=5. f(5) lies on the other line since 2<5<6 so f(5) is 5-2=3.
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    (Original post by bigdonger;[url="tel:66436108")
    66436108[/url]]i don't understand where the 5 comes from how can one know it's 5?
    You are given points which you can use to construct an equation of the line from X=-2 to X=2. Then just plug in X=0 to get the 5
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    (Original post by RDKGames)
    You are given points which you can use to construct an equation of the line from X=-2 to X=2. Then just plug in X=0 to get the 5
    ok thanks and then what about the next bit?
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    (Original post by bigdonger)
    ok thanks and then what about the next bit?
    Same thing with the right hand side of the function that has the positive gradient.
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    (Original post by RDKGames)
    Same thing with the right hand side of the function that has the positive gradient.
    so i get the equation of the line then set y =0?
    i really don't understand what i'm doing here

    Edit: sorry i got it now, you set x=5 and i got 3 thanks
 
 
 
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