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C1 Maths Help: Surds - Where did I go wrong in this question? Watch

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    10/r5 + 4/r5-r7

    10r5-10r7 + 4r5/r5(r5-r7)

    14r5 – 10r7/5 – r35

    (14r5 – 10r7)(5 + r5r7)

    70r5 + 70r7 – 50r7– 70r5

    20r7



    Should be -2r7
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    I can't follow this. If you write it up in LaTeX or upload an image I may be able to help you.
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    Do them seperatley then put them together. So do 10r3/r15 first to get 2r5. then do the second bit to get -2r5 -2r7.
    put then together to get

    2r5 - 2r5 - 2r7

    the 2r5 and -2r5 cancel so you are left with -2r7

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    Hope that helps

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    (Original post by ImNervous)
    Do them seperatley then put them together. So do 10r3/r15 first to get 2r5. then do the second bit to get -2r5 -2r7.
    put then together to get

    2r5 - 2r5 - 2r7

    the 2r5 and -2r5 cancel so you are left with -2r7

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    Ah thank you sooo much! You're fantastic!
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    No problem

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    (Original post by creativebuzz)
    10/r5 + 4/r5-r7

    10r5-10r7 + 4r5/r5(r5-r7)

    14r5 – 10r7/5 – r35

    (14r5 – 10r7)(5 + r5r7)

    70r5 + 70r7 – 50r7– 70r5

    20r7



    Should be -2r7
    Multiply both sides by the second denominator over the second denominator but with a plus sign (it's pair)
 
 
 
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