1、原式=(n+1)[n(n+2)-3n]=(n+1)(n^2-n)=n(n-1)(n+1)
2、原式=(x-2)[x+1-(3-x)]=(x-2)(2x-2)=2(x-2)(x-1)
3、原式=(a+2b)^2-c^2=(a+2b+c)(a+2b-c)
4、原式=4-(2m-3n)^2=(2+2m-3n)(2-2m+3n)
5、原式=(x-3)^2-z^2=(x-3+z)(x-3-z)�ǵģ��ողŷ�������˵
n(n+1)(n+2)-3n(n+1) =
(x+1)(x-2)+(2-x)(3-x) =
a2+4ab+4b2-c2 =
4-4m2+12mn-9n2=
9+x2-z2-6x