把下列各式因式分解: (1)-a2-1+2a=_; (2)2x2y-x3-xy2=_; (3)(x2+1)2-4x2=_; (4)(x+y)2-2(x2-y2)+(x-y)2=_.

问题描述:

把下列各式因式分解:
(1)-a2-1+2a=______;
(2)2x2y-x3-xy2=______;
(3)(x2+1)2-4x2=______;
(4)(x+y)2-2(x2-y2)+(x-y)2=______.

(1)原式=-(a-1)2
(2)原式=-x(x-y)2
(3)原式=(x+1)2(x-1)2
(4)原式=(x+y-x+y)2=4y2