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