以下过程有何问题？ 设x=1,y=1设x=1,y=1设x=1,y=1 x=yx=yx=y x2=xyx^2=xyx2=xy x2−y2=xy−y2x^2-y^2=xy-y^2x2−y2=xy−y2 (x+y)(x−y)=y(x−y)(x+y)(x-y)=y(x-y)(x+y)(x−y)=y(x−y) x+y=yx+y=yx+y=y 带入x=1,y=1带入x=1,y=1带入x=1,y=1 1+1=11+1=11+1=1 2=12=12=1
