x=t+1/t (1)y=t-1/t (2)(1)+(2)得：2t=x+yt=(x+y)/2将t=(x+y)/2代入（1）得：x=(x+y)/2+2/(x+y)两边同乘以2(x+y)得：2x(x+y)=(x+y)²+42x²+2xy=x²+2xy+y²+4x²-y²-4=0
