x²+y²+2xy分之x²-4y² ÷x²+xy分之2y+x
=(x+2y)(x-2y)/(x+y)²×x(x+y)/(x+2y)
=x(x-2y)/(x+y)
手机提问的朋友在客户端右上角评价点【满意】即可.