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    Help please !
    / = square root

    11. 1/28 - 2/63 + /7
    13. 3/80 - 2/20 + 5/45
    15. /12 + 3/48 + /75
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    thanks in advance =)
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    \sqrt{ab} = \sqrt{a} \times \sqrt{b}

    Does that help at all?
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    (Original post by BJack)
    \sqrt{ab} = \sqrt{a} \times \sqrt{b}

    Does that help at all?
    No lol... well i got through other sums, but these one... nay!!
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    (Original post by Xaraaa)
    No lol... well i got through other sums, but these one... nay!!
    Look at number 11.

    1\sqrt{28} -2\sqrt{63} + \sqrt{7} = (1 \times \sqrt{4} \times \sqrt{7}) - (2 \times \sqrt{9} \times \sqrt{7}) + \sqrt{7}

    How else could you write \sqrt{4} , \sqrt{9}?
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    11:  \sqrt 28 = \sqrt 4 \sqrt 7 and  \sqrt 63 = \sqrt 9 \sqrt 7

    For 13, try putting it terms of \sqrt 5 and for 15, try putting it in terms of \sqrt 3.
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    (Original post by Xaraaa)
    Help please !
    / = square root

    11. 1/28 - 2/63 + /7
    13. 3/80 - 2/20 + 5/45
    15. /12 + 3/48 + /75

    so is question 11. \sqrt 28 - 2 \sqrt 63 + \sqrt 7 ?

    for starters we know \sqrt 28 = \sqrt 7 X \sqrt 4
    2 \sqrt 63= 2 X (\sqrt 7 x \sqrt 9)

    these simplify to 2 \sqrt 7 - 6 \sqrt 7+ \sqrt 7 = -3 \sqrt 7 ..i think

    sorry my latex isnt too good!
 
 
 
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