因为：x2-x-1=0 ,所以
(x2-x-1)*(x-a)
=x3-x2-x-a*x2+a*x+a
=x3-(1+a)x2+(a-1)x+a=0
令a=1,有：x3-2x2=-1
则：-x3+2x2+2006=-（x3-2x2)+2006
=2007