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Homework Help: Simplifying Cubed Roots

  1. May 17, 2012 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations
    Starting Equation:

    ³√9xy^4 * ³√12x³y

    3. The attempt at a solution

    (Sorry ahead of time if this is sloppy)

    ³√9xy^4 * ³√12x³y - I broke up each part of the cubed roots to try and simplify them

    ³√9 * ³√x * ³√y * ³√y³ * ³√y * ³√12 * ³√x³ * ³√y³ - I then simplified the obvious cubed roots, and simplified √12 to 2√3:

    y * ³√9xy * 2x * ³√3y - This is where I'm stuck.

    I don't understand how I can simplify if further when 9 has no rational number that can be multiplied by itself 3 times to get to 9, yet apparently the answer to it doesn't have 9 under the radical.

    The answer, to help out anybody who wants to help me, is:

    3xy * ³√4xy²

    Thanks for any help.
    Last edited: May 17, 2012
  2. jcsd
  3. May 17, 2012 #2


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    Homework Helper

    What is really under the roots? Use parentheses! Bring everything under a single cubic root.

  4. May 17, 2012 #3

    Alright, thanks for the help. So, since I have a coefficient and similar variables under the cubed roots, I can change around where they all go?

    And at first, I thought ehild was trying to call me a child for not knowing the answer, and just misspelled it.....
    Last edited by a moderator: May 21, 2012
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