ax三次方y+axy三次方-2ax平方y平方,=axy(x²+y²-2xy)=axy(x-y)²x平方（x-y）+（y-x）,=x²(x-y)-(x-y)=(x-y)(x²-1)=(x-y)(x+1)(x-1)（y平方+4）平方-16y平方=(y²+4+4y)(y²+4-4y)=(...