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Math Help - How to find X

  1. #1
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    How to find X

    Hello,
    This is a lame questions, but my brain is fried and having trouble getting this

    I have y=x^3 with y = 8

    How do I find X
    do I multiply both sides by 3 root then I have
    3root of 8=x??

    Thanks
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  2. #2
    MHF Contributor Siron's Avatar
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    Re: How to find X

    You can do it like this:
    y=x^3
    \Leftrightarrow \sqrt[3]{y}=\sqrt[3]{x^3}
    ...
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  3. #3
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    Re: How to find X

    OK I was reading something.
    So I have 8=y^3.
    So I raise both sides to 1/3 to cancel out the 3 on the x side.

    so it's 8^1/3=x??
    Do I have this correct?? from what I just read
    Last edited by bradycat; August 10th 2011 at 08:51 AM.
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  4. #4
    MHF Contributor Siron's Avatar
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    Re: How to find X

    I take the 3th root of each side, yes indeed take the 3th root of 8, which is? ...
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  5. #5
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    Re: How to find X

    I changed the 840am response. Check that one
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  6. #6
    MHF Contributor Siron's Avatar
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    Re: How to find X

    Quote Originally Posted by bradycat View Post

    so it's 8^1/3=x??
    Do I have this correct?? from what I just read
    This is correct, so x=...?
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  7. #7
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    Re: How to find X

    X=2.
    THANKS ALL FOR YOUR HELP. I got this understanding now.
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  8. #8
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    Re: How to find X

    Quote Originally Posted by bradycat View Post
    I changed the 840am response. Check that one
    Just a note: most people on MHF have time set to their local time zone. This is an international forum, and we probably have about every time zone represented. Your "8:40" response reads as "12:40" on my computer. It's better to refer to post #, which is in the upper right corner of all posts.
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  9. #9
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    Re: How to find X

    Probably the best way to solve x^3= 8 is to recognize that 8= 2^3. So the equation is x^3= 2^3 and so x= 2.
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  10. #10
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    Re: How to find X

    Quote Originally Posted by bradycat View Post
    Hello,
    This is a lame questions, but my brain is fried and having trouble getting this

    I have y=x^3 with y = 8

    How do I find X
    do I multiply both sides by 3 root then I have
    3root of 8=x??

    Thanks
    Do you need to find the real cube root of 8, or do you need to find all three third roots of 8?
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