问题
解答题
把下列各式分解因式：
（1）x3+x2y-xy2-y3；
（2）（a2+2）（a2+1）-30．
答案
（1）x3+x2y-xy2-y3
=(x3+x2y)-(xy2+y3) =x2(x+y)-y2(x+y) =(x+y)(x2-y2) =(x+y)(x+y)(x-y) =(x+y)2(x-y)
（2）（a2+2）（a2+1）-30
=a4+3a2+2-30 =a4+3a2-28 =(a2-4)(a2+7) =(a+2)(a-2)(a2+7)