x²-2xy=x(x-2y)=0 (1)x²-y²+2y-1=x²-(y-1)²=(x+y-1)(x-y+1)=0 (2)由(1)得 x=0 (3)或 x-2y=0 (4)把(3)代入(2)得 (y-1)²=0即 y1=y2=1把(4)代入(2)得 (3y-1)(y+1)=0从而 y3=1/3 y4=-1从...