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Algebra help! Simplify completely?

Simplify completely: [cube root (x^6y^4 / 3z^3) ] * [cube root (81x^9y^-10z^6) ]

Update:

Y is raised to the power of -10...you just read the problem differently

2 Answers

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  • 9 years ago
    Favourite answer

    CubeRoots (like square roots or any other level of roots) can be "distributed" over products.

    CubeRoot(a) * CubeRoot(b) =

    CubeRoot(ab)

    Multiply (x^6y^4 / 3z^3)

    by (81x^9y^2-10z^6)

    *** you are missing the exponent for y in the second cubeRoot **

    I am using 2 for now, but you have to do the problem with the real one in your problem

    and you get [(27x^15 y^6 / z^3) - (10/3)x^6 y^4 z^3]

    From here, it gets tricky, as a root can NOT be distributed over sums and differences

    cubeRoot(a-b) is NOT the same as cubeRoot(a) - cubeRoot(b)

    try to factor out common stuff.

    [(27x^15 y^6 / z^3) - (10/3)x^6 y^4 z^3]

    I would factor out 27 (yes), x^6, y^6 and z^3

    to get:

    (27x^6 y^6 z^3) [(x^9 / z^6) - (10/81)/y^2 ]

    What do we have, so far?

    cubeRoot(x^6y^4/3z^3) * cubeRoot(81x^9y^2 - 10z^6)

    becomes

    cubeRoot [(27x^15 y^6 / z^3) - (10/3)x^6 y^4 z^3]

    becomes

    cubeRoot {(27x^6 y^6 z^3) [(x^9 / z^6) - (10/81)/y^2 ]}

    becomes

    cubeRoot(27x^6 y^6 z^3) * cubeRoot[(x^9 / z^6) - (10/81)/y^2 ]

    solve the first root:

    3x^2y^2z * cubeRoot[(x^9 / z^6) - (10/81)/y^2 ]

    The next step is to factor the remaining part of the root. In such problems, you normally get a "difference of powers" where there are tricks to factor. But because I do not know the original power of y, I would only be guessing.

  • Moon
    Lv 7
    9 years ago

    The question has not been written properly, and apparently carries some mistakes.

    First ensure the accuracy!

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