9x^4 - 9x^3 - x^2 +x+2x-2
9x^3(x-1)-x(x-1)+2(x-1)
(x-1)×(9x^2 - x+2)
(x-1)(9x^3 - 4x+3x+2+6x^2 - 6x^2)
(x-1)(3x^2 ×(3x+2) - 2x×(3x+2) +1(3x+2))
(x-1)(3x+2)(3x^2 - 2x+1)
9x^4 - 9x^3 - x^2 +x+2x-2
9x^3(x-1)-x(x-1)+2(x-1)
(x-1)×(9x^2 - x+2)
(x-1)(9x^3 - 4x+3x+2+6x^2 - 6x^2)
(x-1)(3x^2 ×(3x+2) - 2x×(3x+2) +1(3x+2))
(x-1)(3x+2)(3x^2 - 2x+1)