问题 填空题 若x2-2x-1=0,那么x2+1x2的值为______. 答案 ∵x2-2x-1=0,∴x2-1=2x,∴x2+1x2=x4+1x2=(x2-1)2+2x2x2=4x2+2x2x2=6.