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Math Help - Error in a qoutient

  1. #1
    Junior Member
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    Error in a qoutient

    Hi there, I'm doing some basic data handling, at the moment I'm on sources of error i.e measured values and fractional errors.

    I've attached a scan of the page.

    My question is how do you come to a/b(fa-fb)?
    I know Q=a/b
    Qm=a(1+fa)/b(1+fb)

    so Qm-Q=a(1+fa)/b(1+fb) - a/b so i factorise to get a/b(1+fa/1+fb - 1)

    which equals a/b(fa-fb/1+fb)...so from here I don't know how to get the result in the book.

    Thanks.
    Attached Thumbnails Attached Thumbnails Error in a qoutient-scan-3.jpg  
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  2. #2
    Grand Panjandrum
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    Re: Error in a qoutient

    Quote Originally Posted by flashylightsmeow View Post
    Hi there, I'm doing some basic data handling, at the moment I'm on sources of error i.e measured values and fractional errors.

    I've attached a scan of the page.

    My question is how do you come to a/b(fa-fb)?
    I know Q=a/b
    Qm=a(1+fa)/b(1+fb)

    so Qm-Q=a(1+fa)/b(1+fb) - a/b so i factorise to get a/b(1+fa/1+fb - 1)

    which equals a/b(fa-fb/1+fb)...so from here I don't know how to get the result in the book.

    Thanks.
    You use a power series expansion of 1/(1+f_b)=1-f_b+O(f_b^2) for small f_b

    CB
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  3. #3
    Junior Member
    Joined
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    Re: Error in a qoutient

    Hi there CB,

    Thanks for your reply, I've actually never touched on power series, would you be able to recommend preceding topics that I will need to study to fully understand them.

    Many thanks

    flm
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  4. #4
    Grand Panjandrum
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    Re: Error in a qoutient

    Quote Originally Posted by flashylightsmeow View Post
    Hi there CB,

    Thanks for your reply, I've actually never touched on power series, would you be able to recommend preceding topics that I will need to study to fully understand them.

    Many thanks

    flm
    In this case you need Newton's generalised binomial theorem.

    CB
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