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Math Help - Radical Operations

  1. #1
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    Radical Operations

    Let sqrt = square root

    sqrt{75} + 2(sqrt{12}) - sqrt{48} =

    My answer is 5(sqrt{3}).

    The book's answer is 20.

    I don't see how 20 can possibly be the answer.

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  2. #2
    MHF Contributor Calculus26's Avatar
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    You are correct

    sqrt{75} + 2(sqrt{12}) - sqrt{48} =

    sqrt(25)sqrt(3) + 2sqrt(4)sqrt(3) -sqrt(16)sqrt(3) =


    5sqrt(3) + 4sqrt(3) -4sqrt(3) = 5sqrt(3)
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  3. #3
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    ok...

    Quote Originally Posted by Calculus26 View Post
    You are correct

    sqrt{75} + 2(sqrt{12}) - sqrt{48} =

    sqrt(25)sqrt(3) + 2sqrt(4)sqrt(3) -sqrt(16)sqrt(3) =


    5sqrt(3) + 4sqrt(3) -4sqrt(3) = 5sqrt(3)
    I better get new books. My Math A and Math B books are full of errors.
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  4. #4
    MHF Contributor Calculus26's Avatar
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    I worked one summer as a grad student doing the answers in the back of the book.

    Paid little to do it so-- in all honesty I'm surprised there as few mistakes as there are.
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  5. #5
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    tell me...

    Quote Originally Posted by Calculus26 View Post
    I worked one summer as a grad student doing the answers in the back of the book.

    Paid little to do it so-- in all honesty I'm surprised there as few mistakes as there are.
    How does one get a job correcting errors posted in the back of math books?
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  6. #6
    MHF Contributor Calculus26's Avatar
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    The author contacted the Math Department looking for someone and the chairman contacted me.
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