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Thread: Surds

  1. #1
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    Surds

    Having trouble solving the following re rationalize denominator & simplify. have answer manual, but cannot figure out how to arrive at the answer.

    cube root of x/2 - cube root of x/16. answer is cube root of 4x over 4.

    converted equation to: cube root of x divided by cube root of 2 - cube root of x divided by cube root of 16, but from here I am lost.
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: Introduction

    Quote Originally Posted by retro View Post
    Having trouble solving the following re rationalize denominator & simplify. have answer manual, but cannot figure out how to arrive at the answer.

    cube root of x/2 - cube root of x/16. answer is cube root of 4x over 4.

    converted equation to: cube root of x divided by cube root of 2 - cube root of x divided by cube root of 16, but from here I am lost.
    You should post your math questions in the appropriate forum here.

    $\displaystyle \sqrt[3]{\frac{x}{2}}-\sqrt[3]{\frac{x}{16}}=\sqrt[3]{x}\left(\frac{1}{\sqrt[3]{2}}-\frac{1}{2\sqrt[3]{2}}\right)= \frac{\sqrt[3]{x}}{2\sqrt[3]{2}}\cdot\frac{\sqrt[3]{4}}{\sqrt[3]{4}}=\frac{\sqrt[3]{4x}}{4}$
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  3. #3
    Forum Admin topsquark's Avatar
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    Re: Surds

    Please make your own thread when asking a new question. The previous thread had nothing to do with this.

    -Dan
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  4. #4
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    Re: Surds

    I don't understand how u arrived at the denominator in the equation cubed root of X/2*cube root of 2

    Also, please tell me how to insert math symbols
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  5. #5
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    Re: Surds

    Quote Originally Posted by retro View Post
    I don't understand how u arrived at the denominator in the equation cubed root of X/2*cube root of 2
    Also, please tell me how to insert math symbols
    To post symbols learn to use LaTeX

    You need to learn the basic algebra of exponents:
    $\large{\sqrt[3]{16}=\sqrt[3]{8\cdot 2}=\sqrt[3]{2^3}\cdot\sqrt[3]{ 2}=2\sqrt[3]{2}}$
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  6. #6
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    Re: Surds

    OMG I have so much to learn. Thanks so much
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