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    I've been trying to figure out this question on surds for half an hour

    Any help?

    1√28 – 2√63 +√7

    Pos Rep to the best soultion

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    Answer is -3√7
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    (Original post by Mist786)
    I've been trying to figure out this question on surds for half an hour

    Any help?

    1√28 – 2√63 +√7

    Pos Rep to the best soultion
    \sqrt{28}=2\sqrt{7}
    similarly what is root 63
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    3 root 7


    Can you simplify further?
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    Make everything respect to \sqrt 7

    \sqrt 28 = 2\sqrt7

    -2\sqrt 63 = -2\times3\sqrt7

    so your equation would be

    -6\sqrt 7 + 2\sqrt 7 + \sqrt 7
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    (Original post by Mist786)
    I've been trying to figure out this question on surds for half an hour

    Any help?

    1√28 – 2√63 +√7

    Pos Rep to the best soultion
    1√28 = 1√(4 x 7) = 2√7
    2√63 = 2√(7 x 9) = 6√7
    √7=√7
    so 1√28 – 2√63 +√7 = 2√7-6√7+√7= -3√7
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    how do you peeps get these maths symbols in your posts?
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    (Original post by DickDastardly)
    how do you peeps get these maths symbols in your posts?
    I copy the symbol from microsoft word
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    Its like getting all fractions with the same denominator. First simplify the surds down so all have root 7 then do what you like with them.
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    (Original post by rushhour72)
    1√28 = 1√(4 x 7) = 2√7
    2√63 = 2√(7 x 9) = 6√7
    √7=√7
    so 1√28 – 2√63 +√7 = 2√7-6√7+√7= -3√7
    How do you get -3?
    Isn't 2-6=-4
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    (Original post by DickDastardly)
    how do you peeps get these maths symbols in your posts?
    Using this thing (I don't know what its properly called) called latex. Learn about it here: http://www.thestudentroom.co.uk/wiki/LaTex
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    (Original post by Mist786)
    How do you get -3?
    Isn't 2-6=-4
    cos u gotta add the √7 to the -4√7
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    1\sqrt{28}-2\sqrt63 +\sqrt7





Split into [1\sqrt{28}] and [2\sqrt63] and [\sqrt7]





1\sqrt28 = 1\sqrt4\sqrt7 = 1\times2\sqrt7 = 2\sqrt7





2\sqrt63 = 2\sqrt9\sqrt7 = 2\times3\sqrt7 = 6\sqrt7





\sqrt7 = \sqrt7





Now put the rewritten values back into the original equation





2\sqrt7-6\sqrt7+\sqrt7 = -3\sqrt7

    Hope that's clear enough!
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    Thanks for the help x
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    (Original post by Mist786)
    Thanks for the help x
    so wheres our rep? x
    • Thread Starter
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    (Original post by rushhour72)
    so wheres our rep? x
    You seem very eagar for rep :p:
    You'll have wait as I have to give rep to others
    Dont worry, you will get rep sometime this week
    Oh, if I forget then PM me x
 
 
 
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