(1)-(2)得
x-y=-4/t
∴t=-(x-y)/4
把 t=-(x-y)/4代入(1)得
x=-(x-y)/4+2/(x-y)-1
4x(x-y)=-(x-y)²+8-4(x-y)
∴5x²-6xy+y²+4x-4y-8=0