x^2-2x-1=0
显然x不等于0
所以两边可以除以x
x-2-1/x=0
x-1/x=2
两边平方
x^2-2+1/x^2=4
x^2+1/x^2=6
x^3-2x-1/x^3+2/x
=(x^3-1/x^3)-2(x-1/x)
=(x-1/x)(x^2+1+1/x^2)-2(x-1/x)
=2*(6+1)-2*2
=10