由xy+x=16,得 x=16/(y+1)代入xy-x=8,得
16y/(y+1)-16/(y+1)=8
=>16(y-1)/(y+1)=8
=>(y-1)/(y+1)=1/2
移项,通分得y-3/2(y+1)=0
=>y=3 代入x=16/(y+1),得
x=4