1、16（a-b）²-9（a+b)²
=[4（a-b)]²-[3(a+b)]²
=(4a-4b)²-(3a+3b)²
=[(4a-4b)+(3a+3b)][(4a-4b)-(3a+3b)]
=(7a-b)(a-7b)
2、x^5y-xy
=xy(x^4-1)
=xy(x^2^2-1)
=xy(x^2+1)(x^2-1)
=xy(x^2+1)(x+1)(x-1)
=xy(x+1)(x-1)(x^2+1)
因式分解最后结果一般由简单到复杂排列
3、2010²-2009²
=(2010+2009)(2010-2009)
=4019*1
=4019