(x+y)(x-y)-(x+y)=0(x+y)(x-y-1)=0若x-y-1=0y=x-1则4x^2-x^2+2x-1+2x-x+1=03x^2-3x=03x(x-1)=0x=0,x=1y=x-1若x+y=0y=-x则4x^2-x^2+2x+x=03x^2+3x=3x(x+1)=0x=0,x=-1y=-x所以x=0,y=-1x=1,y=0x=0,y=0x=-1,y=1