x^2/(x^2-1)-6(x^2-1)/x^2+1=0
两边同乘(x^2-1)x^2
x^4-6(x^2-1)^2+(x^2-1)x^2=0
x^4-6x^4+12x^2-6+x^4-x^2=0
4x^4-11x^2+6=0
由求根公式得x^2=3/4或x^2=2
所以x=±(√3)/2或x=±√2