计算下面式子{x-y+[(4xy)/(x-y)]}{x-y-[(4xy)/(x-y)]}

Question

计算下面式子
{x-y+[(4xy)/(x-y)]}{x-y-[(4xy)/(x-y)]}

Answer 1

=[(x-y)²+4xy]/(x-y) ×[(x+y)²-4xy]/(x+y)
=(x+y)²/(x-y) ×(x-y)²/(x+y)
=(x+y)(x-y)
=x²-y²