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Binomial Expansion and Estimates of Square Roots Watch

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    There's a question like expand  (4-x)^{1/2}

    The expansion's fine and to a degree so is the approximation. Surely an approximation is to get a quick answer without the use of a calculator? Otherwise you might as well just put it straight into the calculator in the first place? My problem is I can do the approximation and get a fraction, but sometimes the fractions are way to complex to do in your head (or on paper quickly) as is converting them to decimal to find the degree of accuracy.

    My question is, what is the point??? In an exam you have a calculator anyway, so everything can be done with it! Even getting the approximate to decimal to check!

    In an exam we wouldn't be expected to do this 'properly' would we? i.e. spend an age getting the approx fraction and then comparing with the actual decimal value?

    Thanks!
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    Not really sure what you are asking

    You would be expected to find each term as a decimal ... You can use your calculator to do that
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    (Original post by TenOfThem)
    Not really sure what you are asking

    You would be expected to find each term as a decimal ... You can use your calculator to do that
    then what is the point in the first place? ... why get an approximation as a decimal when you can just wack the thing straight in the calculator in the first place? ... in the context of the questions, this seems rather pointless to me? cheers!
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    (Original post by tdx)
    then what is the point in the first place? ... why get an approximation as a decimal when you can just wack the thing straight in the calculator in the first place? ... in the context of the questions, this seems rather pointless to me? cheers!
    It is a start to the work on series that is only continued if you study FM or beyond

    Most of Core is technique that has use further on in maths rather than a skill that stands alone
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    (Original post by TenOfThem)
    It is a start to the work on series that is only continued if you study FM or beyond

    Most of Core is technique that has use further on in maths rather than a skill that stands alone
    yeah I know, I'm doing further at the moment as well... just this seems a lot more pointless than half the other stuff. The majority of the rest of the course either involves more mathematical operations (than just subbing a number for x) or actually has a known use to the student at that point of their study. Anyhow, tis my opinion and you have answered my question, that the examiner will require just an understanding of the process and you're not expected to show evidence of manipulating complex fractions to decimals haha :') gracias
 
 
 
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