FOILing (2x2 - x)(2x + 4)
    F Take the product of the First terms 2x2.2x = 4x3
    O Take the product of the Outer terms 2x2.4 = 8x2
    I Take the product of the Inner terms (-x).2x = -2x2
    L Take the product of the Last terms (-x).4 = -4x
    Then add them all up 4x3 + 8x2 - 2x2 - 4x  =  4x3 + 6x2 - 4x

Enter this as   4*x^3 + 6*x^2 - 4*x

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