a, \(=x^2-6x+9+x^3-125-\left(x^3-1\right)=x^2-6x-115\)
b, \(=x^3-3.x^2.2+3.x.4-8-2\left(x^3+27\right)+x^3+3x^2+3x+1=-6x^2+12x-8-54+3x^2+3x+1=-3x^2+15x-61\)
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