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Homework Help: Solving Surds

  1. Mar 20, 2008 #1
    im having trouble trying to figure out a problem. can someone help me.

    (2/6 -root3)^2 - (2/6+root3)^2

    if that makes sense to anyone help.

    I think that the denominator of both has to be rationalised but do i expand the squared brackets first or later or what?

    any ideas welcome thanks
  2. jcsd
  3. Mar 20, 2008 #2
    I think you can use the difference of 2 squares a^2 - b^2 = ( a+b) (a-b). good luck!
  4. Mar 20, 2008 #3
    Do you mean

    [tex]\left(\frac{2}{6-\sqrt{3}}\right)^2 - \left(\frac{2}{6+\sqrt{3}}\right)^2[/tex]

    What are you supposed to do with this? Simplify?
  5. Mar 21, 2008 #4
    Don't expand first. Use a^2 - b^2 = (a+b) (a-b) as tram said, at denominator, remember to do two times due to the square. This is to make denominator a whole number. Account for the multiplication for the numerator too.
  6. Mar 23, 2008 #5
    I am supposed to evaluate it.
    And thanks for all the advice by the way.
    Last edited: Mar 23, 2008
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