分解因式(1)a^2-4(2)-1+a^2(3)-1+(a-b)^2(4)x^2y^2-1(5)4a^2-25(6)x^2-9y^2(7)36-25x^2(8)x^2y^2-z^2老师让做题，怎么分解这些因式啊？郁闷啊= =
问题描述：
分解因式(1)a^2-4(2)-1+a^2(3)-1+(a-b)^2(4)x^2y^2-1(5)4a^2-25(6)x^2-9y^2(7)36-25x^2(8)x^2y^2-z^2
老师让做题，怎么分解这些因式啊？郁闷啊= =
答
（1）a^2-4=(a+2)(a-2)
(2) -1+a^2=a^2-1=(a+1)(a-1)
(3) -1+(a-b)^2=(a-b+1)(a-b-1)
(4)x^2y^2-1=(xy+1)(xy-1)
(5)4a^2-25=(2a+5)(2a-5)
(6)x^2-9y^2=(x+3y)(x-3y)
(7)36-25x^2=(6+5x)(6-5x)
(8) x^2y^2-z^2=(xy+z)(xy-z)