a) \(x^3-4x^2-8x+8\)
\(=x^3+8-4x^2-8x\)
\(=\left(x+2\right)\left(x^2-2x+4\right)-4x\left(x+2\right)\)
\(=\left(x+2\right)\left(x^2-2x+4-4x\right)\)
\(=\left(x+2\right)\left(x^2-6x+4\right)\)
\(=\left(x+2\right)\left(x^2-6x+9-5\right)\)
\(=\left(x+2\right)\left[\left(x-3\right)^2-5\right]\)
\(=\left(x+2\right)\left(x-3-\sqrt{5}\right)\left(x-3+\sqrt{5}\right)\)
b) \(1+6x-6x^2-x\)
\(=1-x+6x\left(1-x\right)\)
\(=\left(1-x\right)\left(6x+1\right)\)
c) \(6x^3-x^2-486x+81\)
\(=x^2\left(6x-1\right)-8x\left(6x-1\right)\)
\(=\left(6x-1\right)\left(x^2-8x\right)\)
\(=x\left(6x-1\right)\left(x-8\right)\)
\(x^4-4x^2+4x-1\)
\(=x^4-1-4x^2+4x\)
\(=\left(x-1\right)\left(.........\right)-4x\left(x-1\right)\)
\(=\left(x-1\right)\left(......-4x\right)\)