1）a的三次方m的四次方—49a

1,=a(a^2m^4-49)
=a(am^2+7)(am^2-7)
2,=x^2n(x^2-1)
=x^2n(x+1)(x-1)
3,=1/2(x^4-4y^4)
=1/2(x^2+2y^2)(x^2-2y^2)
=1/2(x^2+2y^2)(x-根号2 y)(x+根号2 y)
4,=(7a-8b+2x)(7a-8b-2x)
5,=(a+b-a+2b)(a+b+a-2b)
=3b(2a-b)
6,=[(2x-y)^2+(2x+y)^2][(2x-y)^2-(2x+y)^2]
=(8x^2+2y^2)(-4xy)