6x^3-11x^2+x+4
=(6x³-6x²)-5x²+x+4
=6x²(x-1)-(5x²-x-4)
=6x²(x-1)-(5x+4)(x-1)
=(x-1)((6x²-5x-4)
=(x-1)(3x-4)(2x+1)