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Math Help - Working with square roots - preparing for GRE

  1. #1
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    Working with square roots - preparing for GRE

    Math is absolutely my worst subject and I am now struggling to learn math all over again in preparation for my GRE. Can you please help me solve and explain the two following problems?

    (√300) ∕ (√12)

    (√5) (√2) - √90

    Thank you
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  2. #2
    Member Last_Singularity's Avatar
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    Quote Originally Posted by tbee View Post
    Math is absolutely my worst subject and I am now struggling to learn math all over again in preparation for my GRE. Can you please help me solve and explain the two following problems?

    (√300) ∕ (√12)

    (√5) (√2) - √90

    Thank you
    Note that \sqrt{x} \sqrt{y} = \sqrt{xy}, so for example, \sqrt{5} \sqrt{2}=\sqrt{10}

    And \sqrt{x}/\sqrt{y} = \sqrt{x/y}, so for example, \sqrt{300}/ \sqrt{12} = \sqrt{300/12}
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  3. #3
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    Thanks, how about the second problem. The book answer is -2√10 and I can't figure out how they came up with that since you can only add/subtract when numbers inside square root are identical and have no idea of how to break it down.
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  4. #4
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    \sqrt{5}\sqrt{2} - \sqrt{90}

    \sqrt{(2)(5)}- \sqrt{(9)(10)}

    \sqrt{10} - \sqrt{9} \sqrt{10}

    \sqrt{10} - 3 \sqrt{10}

    - 2 \sqrt{10}
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  5. #5
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    Quote Originally Posted by tbee View Post
    Math is absolutely my worst subject and I am now struggling to learn math all over again in preparation for my GRE. Can you please help me solve and explain the two following problems?

    (√300) ∕ (√12)

    (√5) (√2) - √90

    Thank you
    the solution is:
    =10 redical 3 / 2 redical 3
    =5

    redical 10 - 3 redical 10
    = -2 redical 10
    Last edited by lebanon; January 15th 2009 at 06:10 AM.
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  6. #6
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    Roots

    Hello lebanon
    Quote Originally Posted by lebanon View Post
    the solution is:
    =10 redical 3 / 2 redical 3
    =8 redical 3

    redical 10 - 3 redical 10
    = -2 redical 10
    Your first solution above is the answer to the problem \sqrt{300} - \sqrt{12}, not \sqrt{300} / \sqrt{12}. This is because \sqrt{300} = \sqrt{100\times 3} = 10\sqrt{3} and \sqrt{12} = \sqrt{4\times 3} = 2\sqrt{3}. Is that you meant?

    Grandad
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