x^3-x-6x-6=0
x(x^2-1)-6(x+1)=0
x(x+1)(x-1)-6(x+1)=0
(x+1)[x(x-1)-6]=0
(x+1)(x^2-x-6)=0
(x+1)(x-3)(x+2)=0
得：x=-1 x=3 x=-2