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Help With Rationalising The Denominator Of Surds watch

    • Thread Starter
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    Hi
    I suck at surds!
    Can anyone help with this question?
    How do I rationalise this denominator?

    5 divided by 3 square root 5

    I've tried multiplying by root 5 over root 5 but the answer wouldn't fit in the answer space (on my maths)

    thanks
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    multiply by 3 root 5 over 3 root 5
    • Thread Starter
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    sorry its 5 divided by 3 plus square root 5
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    Multiply the top and the bottom by 3 - sqaureroot of 5.



    My bad. *headdesk*
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    Multiply top and bottom by 3 - squareroot of 5
    • Thread Starter
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    thanks just worked it out myself but thanks anyway
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    why 3 - not + sorry?
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    You use the opposite sign. It comes from the difference of 2 squares.

    (a+b)(a-b) = a^2 -b^2

    (a+\sqrt{b})(a-\sqrt{b}) = a^2 - b
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    of course! thank you so much
 
 
 
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Updated: October 2, 2010

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