令X＋X分之1=y
2(y²-2)-3y-1=0
2y²-3y-5=0
(2y-5)(y+1)=0
y1=5/2
y2=-1
x+1/x=5/2或x+1/x=-1(此方程无实数解)
x1=2,x2=1/2
检验符合