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Math Help - Am I expanding this correctly?

  1. #1
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    Am I expanding this correctly?

    Did very good on my last test, so I'll have to keep coming here for advice

    How would I expand:

    (x-3)(x+5)(3x+6)

    Is it:

    x2 - 5x +3x2 + 6x -3x - 15 -9x - 18

    4x2 - 11x - 33 ?
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: Am I expanding this correctly?

    You need to expect that the product of 3 linear factors will be a cubic expression. You should get:

    3x^3+12x^2-33x-90
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  3. #3
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    Re: Am I expanding this correctly?

    Ah I see how you did that now.

    Thanks for clarifying.
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