х³-5x²-6x = x²*(x-1)+2*(x²-5x+4) =x²*(x-1)+2*(x²-x-4x+4)=
==x²*(x-1)+2*(x*(x-1)-4*(x-1))==x²*(x-1)+2*(x-1)*(x-4)=(x-1)*(x²+2*(x-4))=
=(x-1)*(x²+2x-8)=(x-1)*(x²-2x+4x-8)=(x-1)*(x*(x-2)+4*(x-2))=(x-1)*(x-2)*(x+4).
