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Thread: Factorising a cubic.

  1. April 22nd 2010, 11:16 AM #1
    ehsangha
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    Factorising a cubic.

    Hi

    I have a question about algebra

    for example 8t^3 - 27 how to convert to this model

    (2t - 3)(4t^2 + 6t + 9)
    Last edited by mr fantastic; April 22nd 2010 at 03:57 PM. Reason: Re-titled post.
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  2. April 22nd 2010, 12:26 PM #2
    e^(i*pi)
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    Quote Originally Posted by ehsangha View Post
    Hi

    I have a question about algebra

    for example 8t^3 - 27 how to convert to this model

    (2t - 3)(4t^2 + 6t + 9)
    It is the difference of two cubes formula

    (a\pm b)^3 = (a \pm b)(a^2 \mp ab + b^2)

    In your case:

    8t^3-27 = (2t)^3-3^3
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