x^2-6x+1=0两边除以x得x-6+1/x=0∴x+1/x=6(x-1/x)²=x²-2+1/x²=(x+1/x)²-4=32∴x-1/x=±4√2∴x²-1/x²=(x+1/x)(x-1/x)=6×(±4√2)=±24√2
