2.=3(x^2- 1)=3(x- 1)(x+ 1)

3.=x(x^2- 1)=x(x- 1)(x+ 1)

4.=a(a^2+4a+4)=a(a+2)^2

5.=a(a+x+ 1)

6.=-4x(x^2+4x+6)

7.=(3a)^4-(2b)^4=[(3a)^2+(2b)^2][(3a)^2(2b)^2]=[(3a)^2+(2b)^2][(3a-2b)(3a+2b)]

8.=(x+y+z)(x+y-z)

9.-0.0 1( 100-x)

10.(x^2+ 1)(x^2- 1)=(x^2+ 1)(x- 1)(x+ 1)