问题
解答题
分解因式
(1)a2-1+b2-2ab
(2)(x2+1)2-4x2
(3)(x+y)2+6(x+y)+9
(4)x4-5x2+4
答案
(1)a2-1+b2-2ab,
=a2+b2-2ab-1,
=(a-b)2-1,
=(a-b+1)(a-b-1);
(2)(x2+1)2-4x2,
=(x2+1+2x)(x2+1-2x),
=(x+1)2(x-1)2;
(3)(x+y)2+6(x+y)+9=(x+y+3)2;
(4)x4-5x2+4,
=(x2-4)(x2-1),
=(x-1)(x+1)(x-2)(x+2).