(1)x^2-4y^2/x^2+2xy+y^2除以x+2y/x^2+xy=(x-2y)(x+2y)/(x+y)^2除以x+2y/x(x+y)=x(x-2y)/(x+y)(2)x+2y/x^2-y^2+y/y^2-x^2-2x/x^2-y^2=(x+2y-y-2x)/(x-y)(x+y)=(y-x)/(x-y)(x+y)=-1/x+y