x²-2x-1=0的两根是x1,x2
则x1+x2=2,x1·x2=-1
则1/x1+1/x2=(x2+x1)/(x1·x2)=-1/2
1/x2·1/x2=1/(x1·x2)=-1
∴所求的方程是x²+1/2x-1=0