1、(1)a(x-y+z)
(2)3ab(2a-5b+10ab)
(3)5(y-x) (2ay-2ax-b)
(4) (a-x) (a-y) (x-y)
2、(1)31.4
(2)3.256
(3)999984
(4)10000
3、100 V
4、(1) (x-3a) ²
(2)4(x+5)(x-25)
(3) (5m-8) ²
(4) (0.7x+12y) (0.7x-12y)
5、(1)y² (y+1)(y-1)
(2)3a(x+y)(x-y)
(3)4x=(x²-2x+1)=4x(x-1)²
(4) (a-b-c) ²