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Math Help - cubed root

  1. #1
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    cubed root

    \sqrt{6x+9}+5 = 2
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  2. #2
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    it i ssuposed to be a cubed root not a sqaure root i did not know how to make the formula with a square root
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by imbadatmath View Post
    it i ssuposed to be a cubed root not a sqaure root i did not know how to make the formula with a square root
    this is very similar to the question we did for your earlier with the square root. subtract 5 from both sides, and then cube both sides

    use [tex]\sqrt[3]{6x + 9}[/tex] to get \sqrt[3]{6x + 9}
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    oo ok thx
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  5. #5
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    i subtracted 3 from both sides then i multiplied both sides by 3 so i got the equation to be

    6x+9=-27
    i then subtracted 9 from both sides
    6x=-36
    i then divided both sides by 6 and got the answer to be -6
    but when i plug it in 6*-6=-36+9=-27 and u cant sq or cube ruoute negative number am i doing something wronge
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  6. #6
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    even if i had a positive 27 the answer still does not come out to be 2 it comes out to be 8 if i di devrything correctly
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  7. #7
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    nvm i was squaring it instead of taking the cued root it iwll work if i take the absolute value of -27
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  8. #8
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by imbadatmath View Post
    nvm i was squaring it instead of taking the cued root it iwll work if i take the absolute value of -27
    Why would you suddenly take an absolute value? If the equation comes up with a -27 then that's what comes up. You can't just change it.

    As a matter of fact you can take the cube root of -27. It is -3.

    -Dan
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