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    Name:  image.jpg
Views: 92
Size:  500.2 KBFrom AQA MPC4 Jun 13

    Question is attached; I have no idea how to do the last part of the Q

    Any guidance is very much appreciated, thanks
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    What happens when x = 1/6 ?
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    We want to use our expansion to approximate the cube root. So we plug x=1/6 into the expansion as this makes the denominator 28.
    However we need 2 lots of this so we multiply the expansion in bi) by 2. Then just use a calculator to give the answer to 6dp.
    Just say if you need any more help cos I don't think I have explained this too well.
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    (Original post by EricPiphany)
    What happens when x = 1/6 ?
    (Original post by B_9710)
    We want to use our expansion to approximate the cube root. So we plug x=1/6 into the expansion as this makes the denominator 28.
    However we need 2 lots of this so we multiply the expansion in bi) by 2. Then just use a calculator to give the answer to 6dp.
    Just say if you need any more help cos I don't think I have explained this too well.
    i dont understand why the jump to x=1/6

    ?
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    (Original post by hi-zen-berg)
    i dont understand why the jump to x=1/6

    ?
    Becuase when subbed into (27+6x)^{-1/3} it gives us yummy yummy which we need
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    Let 27+6x=28
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    You want the denominator to be 28 so that you have cube root of 28 on denominator. So 27+6x=28
    So x=1/6 so you sub that value into your expansion.
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    (Original post by B_9710)
    You want the denominator to be 28 so that you have cube root of 28 on denominator. So 27+6x=28
    So x=1/6 so you sub that value into your expansion.
    Thanks
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    (Original post by EricPiphany)
    Let 27+6x=28
    (Original post by B_9710)
    You want the denominator to be 28 so that you have cube root of 28 on denominator. So 27+6x=28
    So x=1/6 so you sub that value into your expansion.
    ahhhh i see

    thanks guys, big help
 
 
 
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