分解因式:(1-x2)(1-y2)-4xy=_.
问题描述:
分解因式:(1-x2)(1-y2)-4xy=______.
答
(1-x2)(1-y2)-4xy
=1-x2-y2+x2y2-4xy
=1-2xy+x2y2-x2-y2-2xy
=(xy-1)2-(x+y)2
=(xy-1+x+y)(xy-1-x-y).
故答案为:(xy-1+x+y)(xy-1-x-y).