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    Very confused about how you get the answer to 4b, would be super grateful if someone could explain, thanks in advance
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    Link to question please?
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    http://qualifications.pearson.com/co...e_20130618.pdf
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    (Original post by sjmj24)
    Very confused about how you get the answer to 4b, would be super grateful if someone could explain, thanks in advance
    Set 8-9x = to 7100 and then solve for x.
    Then substitute this value of x into your binomial expansion.
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    (Original post by khaleesi98)
    Set 8-9x = to 7100 and then solve for x.
    Then substitute this value of x into your binomial expansion.
    that's what I tried but got completely different answer as they got x=0.1?
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    (Original post by sjmj24)
    that's what I tried but got completely different answer as they got x=0.1?
    Ooh that's worrying 😅 I'm having a look at the mark scheme now.

    If anyone else wants to help it's on this paper...
    http://qualifications.pearson.com/co...e_20130618.pdf
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    (Original post by sjmj24)
    Very confused about how you get the answer to 4b, would be super grateful if someone could explain, thanks in advance
    Let 8 - 9x = 7.1.

    You know the cube root of 1000.

    Does this help?
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    (Original post by ombtom)
    Let 8 - 9x = 7.1.

    You know the cube root of 1000.

    Does this help?
    Yeah that kinda makes sense now I see it, but what's wrong with what me and sjmj24 were going to do?

    ** Ooh is it that x would be too big???
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    (Original post by ombtom)
    Let 8 - 9x = 7.1.

    You know the cube root of 1000.

    Does this help?
    Ahh I see, I got confused as in the mark scheme they had it as 10 times the cube root of 71 maybe I missed a dot somewhere, thank you!
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    (Original post by khaleesi98)
    Yeah that kinda makes sense now I see it, but what's wrong with what me and sjmj24 were going to do?

    ** Ooh is it that x would be too big???
    Yep, the binomial expansion only works for "x" < 1 ("x" being the thing after "1 +").
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    (Original post by ombtom)
    Yep, the binomial expansion only works for "x" < 1 ("x" being the thing after "1 +".
    Ok. sjmj24 listen to him and not me haha x
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    Still both helpful as I understand it better now, if you're doing the C4 paper tomorrow good luck!
 
 
 
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