x+2y+x-2y分之4y平方-x-4y平方分之4x平方y

x+2y+4y^2/(x-2y)-4x^2y/(x-4y^2)
=x+2y+4y^2/(x-2y)-4x^2y/[(x+2y)(x-2y)] 通分,分母为[(x+2y)(x-2y)]
=(x+2y)(x+2y)(x-2y)/[(x+2y)(x-2y)]+[4y^2(x+2y)]/[(x+2y)(x-2y)]-4x^2y/[(x+2y)(x-2y)]
=[(x+2y)^2(x-2y)+4y^2(x+2y)-4x^2y]/[(x+2y)(x-2y)] 一、二项合并
={(x+2y)[(x+2y)(x-2y)+4y^2]-4x^2y}/[(x+2y)(x-2y)]
=[（x+2y)x^2-4x^2y]/[(x+2y)(x-2y)]
=(x^3-2yx^2)/[(x+2y)(x-2y)]
=x^2(x-2y)/[(x+2y)(x-2y)]
=x^2/(x+2y)