2.(a+x)^m+ 1*(b+x)^n- 1-(a+x)^m*(b+x)^n

3.x^2+(a+ 1/a)xy+y^2

4.9a^2-4b^2+4bc-c^2

5.(c-a)^2-4(b-c)(a-b)

The answer is 1. The original formula = a4-a-3a+3 = (a-1) (a3+a2+a-3).

2.[ 1-(a+x)^m][(b+x)^n- 1]

3.(ax+y)( 1/ax+y)

4.9a^2-4b^2+4bc-c^2=(3a)^2-(4b^2-4bc+c^2)=(3a)^2-(2b-c)^2=(3a+2b-c)(3a-2b+c)

5.(c-a)^2-4(b-c)(a-b)

= (c-a)(c-a)-4(ab-b^2-ac+bc)

=c^2-2ac+a^2-4ab+4b^2+4ac-4bc

=c^2+a^2+4b^2-4ab+2ac-4bc

=(a-2b)^2+c^2-(2c)(a-2b)

=(a-2b-c)^2

Adopt it