\((2x+1)^3+(2x-1)^3-24x^2\\=(2x+1+2x-1)^3-3(2x+1)(2x-1)(2x+1+2x-1)-24x^2\\=(4x)^3-3(4x^2-1).4x-24x^2\\=64x^3-48x^3+12x-24x^2\\=16x^3-24x^2+12x\)
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