`#White`
`f(x) = x^5-2x^4+3x^3-4x^2+2`
`= x^5-x^4-x^4+2x^3+x^3-2x^2-2x^2+2`
`= (x^5-x^4)-(x^4-x^3)-(2x^2-2)+(2x^3-2x^2)`
`= x^4(x-1)-x^3(x-1)-2(x^2-1)+2x^2(x-1)`
`= x^4(x-1)-x^3(x-1)-2(x-1)(x+1)+2x^2(x-1)`
`= (x-1)[x^4-x^3-2(x+1)+2x^2]`
`= (x-1)(x^4-x^3-2x-2+2x^2)`
`= (x-1)(x^4-x^3+2x^2-2x-2)`